Popular as part of the power surgery drill assembly 30010 or as a stand-alone to use with the drill of your choice. The chuck will grip diameters from 0 to 1/4” (6.3mm). A stainless key is included.
A 3/8” option and a 1/2” option are available. The 3/8” shaft option has been the historical standard but many drill manufacturers are now utilizing 1/2” diameter shafts. These dimensions are based on the diameter of the threaded shaft of the cordless drill used. The factory chuck is mounted on this shaft and must be removed to determine which drill extension is appropriate.
If you purchased an IMEX drill extension prior to October 2019, it will be the historical 3/8” standard shaft. All 1/2” extensions supplied by IMEX will be laser marked to identify size, as will 3/8” drill extensions going forward. One can also view the base of the extended chuck and visually determine the size based on the threaded hole diameter (related image).