3" x 3" x 1-1/2" x 1-1/2" Reducing Schedule 40 Double Sanitary Tee, All Hub.
3", 3RV- WT, Wall Thimble, Adjusts 4-1/8" To 7" To Fit Wall Thickness, Round Type B Gas Vent.
4", 4RV-WT, Wall Thimble, Adjusts 4-1/8" To 7" To Fit Wall Thickness, Round Type B Gas Vent.