From the manufacturer
The Ambidextrous Safety Selectors are manufactured without screws or threading that could come loose or strip, utilizing stainless steel detent plungers to lock levers into place. The traditional lever (left) side has been built for a more positive feel meanwhile the right side features a lower profile lever and will not interfere with trigger operation for right hand shooters. Constructed of rugged machined billet tool steel, the Ambidextrous Safety Selector is available in semi and full-auto. Patent Pending.
Note: Will NOT Work with non MIL-SPEC receivers or billet receivers (POF, LaRue, custom billet lowers, etc.)