FN SLP Barrel Assembly 24" Inv Plus Modified. This barrel is 24" and comes in a matte black finish. It fits a 12 gauge shotgun and weighs 2.81 lbs. It is produced and machined to the same quality and specifications of the factory FNH 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.