Hex socket: 2.5mm,3mm,3.5mm,4mm,4.5mm,5mm
H4 Hex shank driver 6 oint hex socket used for tightening nuts and bolts.
Is a part of nut driver, can attached to a handle, can provide increased strength and avoid the rounding of rusted or damaged fasteners.
It's an useful hand tool for car repairing in daily use.
not easy to fall off when it's using.