Magnetic base sight. M-Series includes 4 litepipes, 2 red, 2 green. M300: fits ribs from .218" -.328" (7/32 - 21/64"; 5.5 mm - 8.3 mm). Fits Remington: All field models; Browning: Gold 10 ga., BPS, Auto-5; Beretta: Comp., T & ST ribs, Pintail auto; Ruger: Red Label field guns; Ithaca: Model 37 & other models: Benelli: Super Black Eagle & all field guns; Franchi: Field guns. HIVIZ