EGW Springfield 03A3, 03A4 Heavy Duty Scope Bases. Add the versatility of a one-piece Picatinny scope rail. Precision machined from extruded aluminum with Picatinny slot-and-rail spacing that allows fast and simple changes to eye relief, plus great flexibility in scope choice. Accepts Picatinny or Weaver scope rings. Heavy Duty mounts are .100" lower than the Lightweight mounts to minimize weight and keep your optic closer to the barrel centerline for improved accuracy. Full-width cross-slots are gauged to MIL-STD 1913 specs to +/-.002". Machined from ultra-rigid extruded 7075 T6 aluminum. Includes socket head TorxA(R) screws and wrench. EGW recommends 20 inch lbs of t Mfg: Egw Center Spread: 4.1" Overall Length: 5.488" Threads: 8-40TPI Height: Approximately 0.35"