1、4 JAW STRUCTURE: These chucks are of a 4 jaw structure, which provides good contact and strong burr grip, to ensure stable and reliable. 2、HIGH CARBON STEEL: These spring chucks are made of high carbon steel, which has high hardness, impact resistance, and stable performance. 3、MULTIPLE USAGES: These 4 jaw collets are suitable for clamping various grinding head, tool holder, etc., for automotive tires repair and grinding. 4、SPECIFICATIONS: Including 4pcs spring collets, ERG20 series, different sizes to meet different clamping needs, and equipped with boxes for storage. 5、APPLICABLE MACHINE: Widely used in machining center, for ordinary grinder, CNC grinding machine, engraving machine, high speed machine, etc.