This tool changer spindle is specially designed for the Sherline 5000er series. However, you can also use it for any small CNC MILL projects. It important that the two ball bearings accurately fit into a housing bracket. It is a quite simple system, the space between the two ball bearings is sealed by two rubber washers above the bearings adding air pressure. The air presses the internal pneumatic cylinder, and the tool holder is ejected. The tool holder is fixed with a spring in the cone. The tool holder works with ER11 collets (selectable from 1,0 mm to 8,0 mm). Total length: 130 mm. Biggest diameter: 30 mm. Concentricity: 0,01 mm. Maximal spindle speed: 3.000 tpm. ATC Tool changer with 2 rubbers & bearings. Tool holder x 2 ER11 Collets.