HiViz's most economical magnetic sight, the S-Series offers the bare basics to a shooter who knows exactly what color sight he likes. This sight presents a bright, affordable sight picture to any shotgun shooter. LitePipes are not interchangeable, so ?what you see is what you get.?Features:Fits Ultra Narrow Model (S200) fits ribs from .171? to .265? (11/64? to 17/64?) (4.2mm to 6.7mm). Narrow Model (S300) fits ribs from .218? to .328? (7/32? to 21/64?) (5.5mm to 8.3mm). Wide Model (S400) fits ribs from .328? to .437? (21/64? to 7/16?) (8.3mm to 11.1mm).