This extender kit gives you 15mm of additional space to mount another accessory. Some folks want to run a small blinking white light alongside their main illumination light. In the rear facing configuration, this extender allows you to mount two accessories to the mount ie: computer and GPS, or computer and separate heart rate monitor. The possiblities are endless. The kit is composed of a 15mm add on mount, a fitted end cap, and a new longer stainless bolt. This kit allows you to add space to either or both sides of your existing accessory mount.