about this item ?domeNSIONS: total size is 24X14mm, collet reach is 05-3.2mm ?RUSTPROOF, HIGH HARDNESS: This flexible chuck adapter is made of all metal and is extremely durable after heat treatment at high temperature. The black rust oxide on the surface also increases its lifespan. ?PRACTICAL AND EASY TO USE: allows you to quickly and easily change accessory tips. No need to change the chuck when changing between sizes. ?WIDE RANGE OF APPLICATIONS: Applicable to DREMEL original thread 9/32-40, direct inner hole 6.2mm, model is 4000, 400,3000, 398, 395, 300, 285, 275, 200 , 100, 8200, 800, 780, 770 , 7700, 750 ?NOTE: 8050-N/18 cannot be used, the thread can be adapted, but the machine shaft is too short Product Description Specification: Weight : 0.1kg Material: alloy Category: Electric chuck Total length: 23.4mm Tooth width: tooth distance 0.75mm Clamping range: 0.5-3.2mm Clamping range: 0.5- 3.2mm Length: 2.1cm, Diameter: 1.4 cm Use with Rotary Tool Models: 4000, 400, 3000, 398, 395, 300, 285, 275, 200, 100, 8220, 8200, 800, 780, 770, 7700, 750 (Note: Make sure that your Dremel rotary tool model is listed correctly ) Package included: 4 X Keyless Chuck.