Oatey Sure-Vent PVC Air Admittance - 20 DFU -LRB- Drainage Fixture Unit -RRB- capacity. to ASSE -LRB- dweller Society of Safety Engineers -RRB- accepted 1050 and 1051 for use a a unoriginal vent. One size to handle up to 3 '' vent pipe. and closes as needed by building 's plumbing system, 1-1/2 - 2 ''. - : 1-1/2 '' to 2 '', Use on Diameter Branches : Up to 3 '', Material : PVC, Pkg Qty : 1 .