None, the batchs head can be fixed by directly inserting it with force Suitable for professional and DIYer enthusiasts in the field of home maintenance, mechanical maintenance and woodworking Crafted of high qualitys materials, Precisions machining to ensures the closeconnection between the joint and the batchs head; Suitable for screwdriver and power tool 6.35mm handle screwdriver connection, which can connects 1 / 4 batchs head, is and quick to change tool and improve work efficiency Can be widely used in homes decoration, car maintenance, furniture assembly and other scene to meet the different needs of screwdriver conversion, Manufacturer: Kelisdi