The Kinetic Research Group Trigger Guard is the aluminum Whiskey-3 trigger guard that came standard on the gen 3 and 4 chassis. The gen 5 Whiskey-3 and gen 2 X-ray trigger guard was changed to polymer for the Remington 700SA/LA but some shooters just prefer aluminum so it is offered separately. Fits: Bravo Chassis as well as Whiskey-3 and X-ray Chassis for Remington 700SA/LA and Badger 2008/13 SA/LA. Note: Customer will need to use magazine catch, spring, and pivot pin that came with original chassis