The Above the Rail light mount (MPLS-ABR) is designed to free up valuable rail space, for use with communications devices, cameras, or other accessories. This mount is adaptable to several types of helmets, and compatible with Princeton Tec MPLS lights, including Point, Switch, Charge, Charge Pro and Switch Rail.
user manual:
http://princetontec.com/omi/mpls_abr_omi.pdf