Twenty hex sockets for standard 1/4" (6.35 mm) driver bits - the size used by every impact driver, bit set and screwdriver handle on the market. The sockets are hexagonal rather than round, so bits sit square and stay oriented flats-forward; you can read the size stamp without picking each one up. A chamfered mouth on every socket means a bit drops in one-handed even with gloves on. Sockets are 20 mm deep, which holds standard 25 mm insert bits upright with enough sticking out to grab, and still supports longer 50 mm power bits. Small enough to live in a drawer or a tool tote, heavy enough not to skate around the bench. Dimensions: 66 x 53 x 23 mm (2.6 x 2.1 x 0.9 in) Capacity: 20 x 1/4" hex bits Material: PETG, black