There is a Firefield verticle grip light which appears to be the same product as a Leepers UTG 400 Lumen sold by Primary Arms.  My guess is they are Chineese imports with various names.  I do not own any of these but they are very close to the light in the picture you posted.


http://www.primaryarms.com/mnt-el228gpq-a?gclid=CjwKEAjwj6PKBRCAy9-07PeTtGgSJAC1P9xGC190xTK3HBa1lYflfZRG5PMcjoEBS-rNdZAvl_gK8BoCd6Xw_wcB