FNH USA's shotgun choke tubes and accessory spoting barrels enhance the modularity and flexibility of FNH's SLP line. The accessory barrels are of steel construction with a matte black finish for use with the FN SLP and the FN SLP Mark 1 shotguns and are available in 22 inches, 24 inches, 26 inches, 28 inches and 30 inches. The Briley Standard Invector and Invector-Plus extended design choke tubes are polished stainless steel with blue anodized accent identification rings and are offered in sizes from cylinder to extra-full. Also available for the FN SLP and FN SLP Mark 1 is an aluminum tri-rail extension in matte black finish that offers three mounting rails that can be used for tactical lights and lasers.