Gear is a script for 3ds Max, created by Swordslayer, that provides an involute spur gear primitive. The primitive is built with tooth undercut and all-quad topology, giving you spur gear geometry as a primitive object.
One point that sets it apart in the scriptspot library is that the script is unencrypted and fully open for further hacking. The code stays available for anyone who wants to read or modify it. The tool is distributed as a single gear.ms file, weighing in at around 17 KB.
Gear is listed with compatibility for 3DS Max 4.2, and this card covers version 0.03a. Within the scriptspot library the script sits at popularity rank 382. For the reference material behind it, along with the download, head to the developer's page.