This one-piece aluminum base is machined to tight tolerances for a custom fit. It offers maximum strength for rings to hold tight. Screws are included. Fits- BSA Monarch medium action in 222, 243 & 308, long action in 7mm, 270 & 30-06, CF2; Churchill Highlander; Beretta Pintail Slug; Colt Sauer; Rem 721; Herters U9 round receiver; Howa 1500; Mossberg 100 ATR, 1500, 1700, MVP; Raptor Arms; Rem 700, 78, 40X-L, 721 & 725 (long actions), 700, 78, 40X-S, 722 & 725 (short action), 700 Muzzleloader, 783; Sauer 200; Shilen round receiver; S&W 1500, 1600 and 1700; Weatherby Vanguard, Mark V Mag except 240 mag.