Works with both AR-15 and AR-10 lowers. The anti-rotational feature of our stainless steel pins will help lengthen the performance of your AR's lower receiver by not allowing friction against the inner surfaces of the holes. These, along with the Presma Inc anti walk retainer plates , help with preventing premature parts replacement. This Presma Inc Kit comes complete with pin installation tool and the two Torx wrenches. No modifications to your firearm are necessary to install. Kit includes: (1) Trigger Pin - 0.154" diameter (1) Hammer Pin - 0.154" diameter (1) Pin installation tool (2) Anti-Rotating Side Plates - 0.108" thick. Anodized aluminum. (2) Screws (2) Torx wrenches Note: Some AR receivers widths may vary, in trigger and hammer pin area. Pins being too long will not affect performance, but pins can be shortened a small amount. Gently remove material evenly from both ends of each pin by filing. Do not over-tighten the screws, 11 in/lbs max.