Is your light the C-2 Centurion or M-2? Here is their web site information for the C-2:
Good luck with your sale. These are nice lights.
The C2 Centurion utilizes an ergonomic flat-side CombatGrip design and a patented rubber grip ring so that the light can be operated with a handgun using the Rogers/SureFire technique. Powered by two lithium batteries (10-year shelf life), the C2 Centurion produces 65 lumens of light for over an hour, or 120 lumens for 20 minutes using an optional ultra high output lamp. The C2 is precision-machined from aerospace-grade aluminum with an anti-roll bezel and is available in either a Type II anodized black finish, or a super rugged military specification Type III hard anodized finish. A lock-out tailcap allows the light to be locked in the OFF position to prevent accidental discharge of light during tactical operations, transportation, or storage, The C2 also features unique switching originally developed for law enforcement- twist for constant on, or depress the tailcap button for momentary illumination or emergency signaling. Note: The C2 Centurion is similar in design to the M2 Millennium but does not share the M2 Millennium's extra degree of shock isolation and slightly larger bezel.