Material: Hex shank screws power extension holder is made of chrome vanadium steel, high hardness, large torque and durable.Size: 1/4" hex shank (6.35mm), Length: 60mm/100mm/150mm Perfect for drill, screwdriver, batch head and other to transfer.Features: Can extent at 80-120mm,120-200mm,140-240mm,great for exchanging the sleeve and the joint, prolonging the connecting rod.Easy To Use: Lock the connecting rod with strong magnetic, barrel-shaped guide sleeve helps users drill without touching screw.Wide Application: Suitable for extending all kinds of screwdriver bits, drill, batch head, screwdriver head conversion uses. Widely used in situation of narrow space, to reach the work-place where hands can not reach.