VenturiVent Plus, 48" x 12", Shingle Over Ridge Vent With Nails, Vent Is 4' Of Shingle Over Ridge Vent With Bag Of Nails, Preformed To 4/12 Pitch So That The Vent Can Easily Flex From 3/12 To 16/12 Roof Pitches, 18 SQIN Of Net Free Area Per Linear Foot, External Wind Baffle Deflects Wind & Weather Over The Vent, Built-In Ventilating End Plug, Low Profile, Shingle Over Look Of Creates A Clean, Uncluttered Roofline, Installs On The Peak Of The Roof, Allowing Exhaust Ventilation Along The Entire Ridge End To End, 12" Width, Matching Shingles Can Be Installed Over The Vent, Allowing The Vent To Appear Almost Invisible From The Ground, Nail Holes At 16" & 24" Center Make It Easy To Locate & Nail Through Rafters, Easy Installation.