Four interchangeable, high-intensity LitePipes are included with all M-Series sights allowing the shooter to adjust to existing light conditions. The S-Series includes a single LitePipe in your choice of green or red at a more economical price. HiViz?s snap on/off magnetic base is available in four different sizes to fit virtually any rib width from 11/64? to 9/16?. Refer to the selection chart for compatibility. Not compatible with fiber or aluminum ribs. S300 - 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.