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If you own a Volkswagen, Audi, BMW, Mercedes or Porsche, you'll eventually meet a bolt with a 12-point star recess that no Torx or hex bit fits. That's a triple square fastener, also called XZN or 12-point spline. A triple square socket set is the only right tool for it, and it's one of the first specialty sets a European car owner should buy.
Triple square bits look a bit like Torx, but they're not interchangeable. Torx has six rounded lobes; triple square has twelve sharp splines. A Torx bit may drop in loosely, then chew up the fastener when you pull. Common jobs include CV axle bolts, brake caliper carriers, seat bolts, suspension parts and various drivetrain fasteners.
We compared six current triple square sets from Tekton, Capri Tools, VIM Products, Sunex and GearWrench, covering standard, stubby, long and impact-rated options.
Quick Picks
- Best Overall: Tekton SHB99100 (11 pieces). Best for: M4 to M12 with no gaps, plus MT14 to MT18, on a rail.
- Best Value: Capri Tools CP30030 (10 pieces). Best for: three drive sizes from M4 to MT18 in a case.
- Best Master Set: Capri Tools CP30090. Best for: adding M7, M13, M14 and long M10/M12 bits.
- Best Stubby Set: VIM Products VMXZNS412 (6 pieces). Best for: tight spots, with short one-piece drivers from 4 to 12 mm.
- Best Impact Set: Sunex 3640 (8 pieces). Best for: impact-rated stubby sockets from M4 to M16.
- Best Extra-Long Add-On: GearWrench 80572 (4 pieces). Best for: deep-set fasteners in M6 to M12.
Comparison Table
| Product | Best for | Pieces | Drives | Sizes | Length | Impact rated | Storage |
|---|---|---|---|---|---|---|---|
| Tekton SHB99100 | Best overall | 11 | 3/8", 1/2" | M4 to M10, M12; MT14, MT16, MT18 | Standard | No | Rail |
| Capri CP30030 | Value | 10 | 1/4", 3/8", 1/2" | M4 to M6, M8 to M10, M12; MT14, MT16, MT18 | Standard | No | Case |
| Capri CP30090 | Master | 14 (per Capri) | 1/4", 3/8", 1/2" | M4 to M10, M12 to M14; long M10, M12; MT14 to MT18 | Standard + long | No | Case |
| VIM VMXZNS412 | Stubby | 6 | 1/4" | M4, M5, M6, M8, M10, M12 | Stubby | Listed as "impact quality" | Magnetic rail |
| Sunex 3640 | Impact | 8 | 3/8" | M4, M5, M6, M8, M10, M12, M14, M16 | Stubby | Yes | Not specified |
| GearWrench 80572 | Extra long | 4 | 3/8", 1/2" | M6, M8, M10, M12 | Extra long | No | Rail |
The Best Triple Square Socket Sets, Reviewed
1. Tekton SHB99100 11-Piece Set: Best Overall
Who it's for: European car owners who want a gap-free run of the common sizes in a compact rail.
Tekton's set has eight 3/8-inch drive triple square bit sockets (M4, M5, M6, M7, M8, M9, M10 and M12) and three 1/2-inch drive tamper-resistant sizes (MT14, MT16 and MT18). Including M7 and M9 matters: they're the sizes that cheaper sets skip, and they show up on some trim and brake hardware.
The S2 heat-treated steel bits are pressed directly into the sockets for a permanent connection, so they won't loosen or fall out. Everything rides on a 13-inch socket rail, and Tekton notes the set works with a torque wrench, which matters because many triple square fasteners on suspension and drivetrain parts have specific torque specs.
Pros
- M4 to M10 with no gaps, plus M12
- Tamper-resistant MT14 to MT18
- Press-fit bits on a compact rail
Cons
- Not impact rated
- No non-tamper M14 or M16
TEKTON 3/8 Inch Drive Triple Square and 1/2 Inch Drive TR Triple Square Bit Socket Set with Rail, 11-Piece SHB99100
by TEKTON
2. Capri Tools CP30030 10-Piece Set: Best Value
Who it's for: DIYers who need triple square coverage for occasional jobs on a European car.
Capri spreads 10 sizes across three drives: M4, M5 and M6 in 1/4-inch drive; M8, M9 and M10 in 3/8-inch drive; and M12 plus tamper-proof M14, M16 and M18 in 1/2-inch drive. Putting the small bits on a 1/4-inch drive keeps them compact for interior and trim work.
The bits are S2 steel in chrome sockets, and Capri lists a lifetime warranty. Capri's spec table calls the storage a custom molded case and its description calls it a blow-molded box, so expect a hard case either way. It's for hand tools only.
Pros
- Three drive sizes, from M4 to MT18
- Lifetime warranty per Capri
- Small sizes on 1/4-inch drive
Cons
- Skips M7
- Not impact rated
Capri Tools XZN Triple Square Spline Bit Socket Set, Metric, 10-Piece CP30030
by Capri Tools
3. Capri Tools CP30090 Master Set: Best Master Set
Who it's for: owners who work on several European models and want the less-common sizes covered.
The master set adds the sizes the 10-piece leaves out. Capri lists M4, M5 and M6 in 1/4-inch drive; M7, M8, M9 and M10 in 3/8-inch drive; M12, M13 and M14 in 1/2-inch drive; long M10 and M12 bits in 1/2-inch drive; and tamper MT14, MT16 and MT18. The long M10 and M12 are useful for recessed fasteners, such as some CV joint bolts.
Capri sells it as a 14-piece set, but the size list on its page adds up to 15, so check the contents on the listing before you buy if a particular size matters. The bits are heat-treated S2 steel in chrome-vanadium sockets, for hand tools only, with a lifetime warranty.
Pros
- Adds M7, M13, M14 and long M10/M12
- Three drive sizes
- Lifetime warranty per Capri
Cons
- Capri's page lists more sizes than the stated piece count
- Not impact rated
Capri Tools Master XZN Triple Square Spline Bit Socket Set, 14-Piece CP30090
by Capri Tools
4. VIM Products VMXZNS412 Stubby Set: Best Stubby Set
Who it's for: anyone working on triple square bolts in tight spaces, such as seat rails or behind suspension parts.
VIM's VMXZNS412 is a 6-piece set of stubby XZN drivers in 4, 5, 6, 8, 10 and 12 mm. The Amazon listing describes them as 1/4" square drive, one-piece S2 steel, fully heat treated, satin chrome plated and "impact quality", held on a 4" MagRail magnetic organizer. The one-piece stubby design keeps the stack short, so a ratchet fits where a standard bit socket would hit a panel or component.
It is a small set: there are no tamper-proof sizes and nothing above 12 mm, so it won't cover the larger MT14 to MT18 bolts some VW and Audi jobs need. For most owners, it's a second set alongside a standard-length one rather than a replacement.
Pros
- Short, one-piece design for tight spots
- Covers the common 4 to 12 mm sizes
- Magnetic rail keeps the set together
Cons
- Only six sizes, no tamper-proof bits
- Single 1/4" drive, per the listing
VIM Products 6-Piece Stubby XZN Triple Square Driver Set VMXZNS412
by VIM Products
5. Sunex 3640 8-Piece Stubby Impact Set: Best Impact Set
Who it's for: anyone removing triple square bolts with a 3/8-inch impact wrench or impact ratchet.
Most triple square sets use S2 bits pressed into chrome holders, which aren't built for impact. Sunex's 3640 is made of chrome-molybdenum steel and sold as impact sockets: M4, M5, M6, M8, M10, M12, M14 and M16, all stubby, in 3/8-inch drive. Running M14 and M16 on 3/8-inch drive keeps the set compact.
Sunex backs it with a lifetime warranty. Its page doesn't describe storage. Because these are stubby, they're less useful for deep recesses, so pair them with an extension or a long hand set where you need reach.
Pros
- Impact-rated Cr-Mo construction
- M4 to M16 in one drive
- Lifetime warranty per Sunex
Cons
- No M7, M9 or tamper sizes
- Storage not specified
SUNEX 3/8″ Drive Stubby 8-Piece Triple Square Impact Bit Socket Set 3640
by SUNEX
6. GearWrench 80572 4-Piece Extra-Long Set: Best Extra-Long Add-On
Who it's for: owners of a standard triple square set who need to reach deeply recessed fasteners.
GearWrench's 80572 adds extra-long bits in the four most-used mid sizes: M6, M8, M10 and M12, split across 3/8- and 1/2-inch drive, on a socket rail. GearWrench says they're designed for internal triple square fasteners frequently found on European vehicles.
The bits are S2 steel in heat-treated alloy holders, and the set weighs about half a pound. Note that GearWrench classifies it as a consumable with no warranty, unlike most of its sockets.
Pros
- Extra-long reach in the core sizes
- Compact rail
- Light
Cons
- Only four sizes
- No warranty, per GearWrench
GEARWRENCH 4 Piece 3/8″ & 1/2″ Drive Extra Long Triple Square Bit Metric Socket Set 80572
by GEARWRENCH
Triple Square Socket Set Buying Guide
Triple Square vs Torx vs Hex
Triple square (XZN) bits have 12 sharp-cornered splines. Torx bits have six rounded lobes. Hex bits have six flat sides. They are not interchangeable, even when a wrong bit seems to fit. If your car is European, you'll likely need all three; see our Torx socket set and hex socket set guides.
Sizes That Matter
| Size | Typical uses |
|---|---|
| M4 to M6 | Interior trim, small brackets |
| M8 to M10 | Seats, brake components, some suspension |
| M12 | CV axles, some brake carriers |
| M14 to M16 | Drivetrain and some suspension fasteners |
| MT14 to MT18 | Tamper-proof versions of the large sizes |
These are typical examples. Your vehicle's service manual lists exact fasteners and torque specs.
Gaps to Watch
M7 and M9 are the sizes budget sets drop most often. The Tekton SHB99100 and Capri CP30090 include M7; the Tekton and both standard Capri sets include M9. If you need M13 or M14 in standard (non-tamper) form, the Capri CP30090 and Sunex 3640 include M14, and the Capri master set adds M13.
Tamper Sizes
Tamper-proof (MT or TR) bits have a hole in the tip for a center pin. They also fit regular triple square fasteners of the same size, which is why many sets include large sizes only in tamper form.
Bit Length
Standard bits suit most jobs. Stubby bits fit tight spaces. Long and extra-long bits reach recessed fasteners. A standard set plus a long add-on, like the GearWrench 80572, covers most situations.
Impact Rating
Hand-tool triple square sets use S2 bits in chrome holders and aren't designed for impact tools. If you'll use an impact, buy an impact-rated set like the Sunex 3640. Our impact socket set guide explains the construction differences.
Torque Specs
Many triple square fasteners on suspension and drivetrain parts have torque specs, and some are torque-to-yield and meant to be replaced. Use a torque wrench with your bit sockets and a solid 3/8" drive socket set for the rest of the job. Check our socket size chart for the hex sizes on the same jobs.
Storage
Rails (Tekton, GearWrench) keep bits upright and visible; cases (Capri) protect them in a toolbox. Either way, keep triple square bits separate from Torx so you don't grab the wrong one.
Seat the Bit Fully
Triple square fasteners strip easily if the bit isn't fully seated. Clean debris out of the recess, tap the bit in if needed, and keep the ratchet square to the fastener.
How We Chose
We compared current triple square socket sets from Tekton, Capri Tools, Sunex and GearWrench using each manufacturer's published contents and specs: every XZN and tamper size, drive sizes, bit length, bit and socket material, impact rating, storage and listed warranty. We favored sets with gap-free coverage of M4 to M12, and we noted piece-count discrepancies and missing details on manufacturer pages. We also considered recurring owner feedback about stripped fasteners and loose bits. We did not test these sets ourselves.
FAQ
What is a triple square socket used for?
Turning triple square (XZN) fasteners, which have a 12-point internal spline. They are common on European cars from brands such as Volkswagen, Audi, BMW, Mercedes-Benz and Porsche, on parts like CV axles, suspension, brakes, seat mounts and some engine and drivetrain components.
Can I use a Torx bit on a triple square bolt?
No. A Torx bit has six rounded lobes, while a triple square fastener has twelve sharp-cornered splines. A Torx bit may seem to fit loosely but will strip the fastener under load. Use the correct XZN size.
What do the M sizes on a triple square socket mean?
They are the nominal sizes of the spline, in millimeters: M4, M5, M6, M8, M10, M12 and so on. MT sizes, such as MT14 and MT16, are tamper-proof versions with a hole for a center pin.
What triple square sizes do I need?
For most European cars, M6 through M12 handles brakes, seats and much of the suspension, with M14 and M16 common on driveline fasteners. A set covering M4 to M12 plus the larger tamper or standard sizes covers most jobs.
Are triple square sockets impact rated?
Most sets are not. The Tekton SHB99100, Capri sets and GearWrench 80572 are for hand tools only. The Sunex 3640 is an impact-rated stubby set made of chrome-molybdenum steel.
Verdict
The Tekton SHB99100 is the best triple square socket set for most European car owners: M4 to M10 with no gaps, M12 and tamper MT14 to MT18 on a compact rail, with press-fit bits. The Capri CP30030 is the value pick across three drives, and the Sunex 3640 is the one to buy if your triple square bolts will see an impact gun.