clandestine
AR-15 Savant
LaRue stopped making theirs and they are hard to find. Theres always this:
http://www.midwestindustriesinc.com/index.cfm?fuseaction=category.display&category_id=421
http://www.midwestindustriesinc.com/index.cfm?fuseaction=category.display&category_id=421