A full size router plate is a sturdy, flat base plate that mounts to a handheld router, expanding its footprint for stability and precise milling. In firearm DIY, it’s used with 80% lower/router jigs to guide clean, level cuts. Works with compact and full-size routers (pre-drilled bolt patterns), jig top plates, end mills, and plunge mechanisms. Improves control over aluminum or polymer 80% AR-15/AR-10 lowers and pistol frames, reducing wobble and aiding consistent pocket depth.