Set includes one 8 mm with a 3/8" drive base that is 55 mm overall length and 10 and 12 mm with a 1/2" drive base that are 160 mm overall length.
The 8 mm is commonly used for most 4 cyl. drive shaft bolts (where the inner CV bolts to the tranny flange) and more recently, on door lock hardware.
The 10 mm is used on inner CV bolts on cars with 1.8T engines and for some alternator pulleys, starter mounting and flywheel bolts as well as early 1.8T engine bolt heads.
The 12 mm is most commonly used for 1.8 gas, all 4 cyl. diesel, all 4 cyl TDI and VR6® head bolts. The newer MKIV (A4)chassis cars require the 12 mm on the steering wheel center bolt.