18-gauge. 1/4" crown. Ideal for upholstering, cabinet casebacks, drawers, lattice, trim, and light aluminum to wood. For use in Porter Cable model No. NS150, Senco model No. SKS L11-15 and SKS L12-17, DuoFast model No. KN-1848 and BN1832S, Campbell Hausfeld model No. SN 258K00, Hitachi model No. 3804A, and Airy model No. 0645S. 5000 per box.