Rock River Arms Two-Stage Varmint Match Trigger (3.5 Pound Varmint Version) This National Match two-stage trigger from RRA is an excellent trigger for your AR15 rifle. These are used frequently in Varmint and Long Range AR builds where a lighter 2 Stage trigger really helps accuracy and round placement. These triggers come pre-adjusted by Rock River gunsmiths as a matched pair and drop in all mil-spec lowers with no adjustment necessary for an easy drop-in install. Rock River 2-stage NM pins are .1555 in diameter and are not recommended or designed to be used with .154 pins or .170 Colt lower receivers. .1555 RRA Trigger pins will install in any standard milspec lower receiver without modification but may be noticeably more snug than the .154 pins upon install.