Originally Posted by Julien
^ that's such a rip off of the tri force system on the Azodin kaos pump.
Sorry to resurrect an old thread...but that retention system was invented and patented by my old friend Steve K Grimes in the early 90's for easily and quickly slipping photography filters on and off camera lenses.
It's quite possible this clever design was independently "invented" by someone else...
When I was working for Steve and making prototypes of the Killflash anti reflection devices 20 years ago that are now currently being used by the military, I made my own ARD slip on device for my hunting rifle;