XZN Metric Socket Set 8 Piece
OUR BEST SELLER!
These are Triple Square Sockets
XZN means Triple Square (12 point)
If your tool books call for XZN or TRIPLE SQUARE or 12 POINT, these are probably the tools you need. 
These are Short Pattern "Stubby" Sockets
Each tool is 1-1/2 inches long.
Sizes included: M4, M5, M6, M 8, M10, M12, M14 & M16
Short pattern for using when you are in a tight spot.
Sturdy compact solid one piece design.
3/8 Drive Size.
Satin Chrome with black impact tips. New S2 Alloy Steel.
These are some of the strongest drivers you will find.
Comes in the plastic carrying case.

Triple square, also known as a XZN socket, is a type of screw drive. They are commonly found on German vehicles such as BMW, Mercedes, and Volkswagen etc... 
These screws/fasteners are used in some high torque applications such as cylinder head bolts and drive train components. 
Triple square bolts are common to early Porsche and Volkswagen (CV) constant velocity joints.
Most common earlier sizes would be 6, 8, 10, and 12. 
Increasingly, triple square screws are found on other European and Asian makes of cars.
Other names for triple square screws and drivers are "Double Hex", "Double Allen", and "Aircraft Screws". 
Despite this, "Double Hex" and "Double Allen" are misnomers. The recess in these bolts is actually (as the name suggests) made of three squares, not two hexagons. 
The corners are 90 degrees, not 120 degrees. They are not double hexes, and an Allen key will not fit them properly.