ITEM NAME:2 X 3 Mm + 2 X 6 Mm Air Jet Grinding Machines Collet Adapter Description: Chuck size: 6mm, 3mm, for 3mm and 6mm standard grinding bits. High quality car.Suitable for all kinds of grinding machine clamping grinding head. Chuck size: 6mm, 3mm, for 3mm and 6mm standard grinding bits. High precise clamping force, good grip stability. 2 Piece 3mm Air Die Grinder Collect.