FN SLP Barrel Assembly 28" Inv Plus Modified. The barrel is 28" and comes in matte black finish. It fits a 12 gauge shotgun and weighs 3.01 lbs. It is produced and machined to the same quality and specifications of the factory FN SLP barrels. The vent rib and front bead make the barrels ready to use from day one. The flexible magazine capacity reducers ensure that you have the correct capacity depending on the hunt.