Socket wrench set with Flankdrive sockets Flankdrive sockets are made of Chrome vanadium industrial grade steel Sandblasted for oil repellent surface Flankdrive socket's geomitri ensures precise pressure on the flat sides of the bolt/nut. Grooves on all sleeves ensure a good grip. Contents: 14 pcs: 6, 8, 10, 11, 12, 13, 14, 16, 17, 18, 19, 21, 22, 24 mm 6kant. The flank drive sleeves have a precise fit for each dimension. The corners are rounded and the flat surface is slightly convex. This means that the grip is 100% on the flat sides of the nut/bolt. Especially during assembly, this is a guarantee not to damage the head.