The extension connecting link can be installed on hex screw bit. and high quality. Made of galvanized alloy steel, and compact. For the use of connecting the electric screwdriver, screwdriver, wind batch, sleeve, connector adapters, etc. Connecting outer hex into inner hex, magnetic, elongation oriented, non-slip 80mm: Original Length: 80mm(), Max extended length: 118mm(). 120mm: Original Length: 120mm(), Max extended length: 195mm(). Shank diameter: 1/4 inch (6.35mm) color: black Material: Galvanized alloy steel Package contents: 1* 80mm Extension Driver Drill Bit Holder 1* 120mm Extension Driver Drill Bit Holder Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.