Drive spindle extensions allow shanks of grinding and milling tools to be extended. They allow access to hard-to-reach areas and are clamped into the collet of the machine (air or electric grinder) or into the flexible shaft handpiece. Drive spindle extensions are a cost-effective alternative to special made-to-order burs and mounted points with long shanks. Extension for drive spindles with a working length of 150 mm, a tool mounting of 1/4" and a shank holder of 3/8"." Recommended extension for drives with a maximum rotational speed of 10,000 RPM.