Fused-dual-layer design air filters offer combined performance and protection. The fused layers of open-pore foam and fine inner foam trap even the smallest particles. AIRFILTER PRE-OILED- 156016X SHERCO ENDURO SE-R 125 18-24 SE-R 250 13-24 SE-R 300 13-24 SE-F 250 12-24 SE-F 300 12-24 SE-F 450 14-24 SE-F 500 19-24 SE-F 510 14-17