Description: Hex socket:2.5mm,3mm,3.5mm,4mm,4.5mm,5mm. Mini size:28 x 5mm(L*D);Max size:28 x 7mm(L*D) H4 hex shank driver 6 point hex socket, a part of nut driver, can attached to a handle, used for tightening nuts and bolts. Can provide increased strength and avoid the rounding of rusted or damaged fasteners. An useful hand tool for repairing in daily use.