1 piece construction eliminates any possibility of the collar coming off. Patent pending. Patented positive double seal ensures leak free fit around vent stack. Black color blends with modern roofing material colors and is an excellent weathering color. No Caulk collar allows plenty of room for expansion and movement of pipe. Gives with the movement of the pipe while maintaining leakproof seal. Fits roof angles from flat to 45. Will not warp or crack. Never needs caulking. Fits all types of pipe, copper, cast iron, plastic, aluminum, and galvanized. Easy to install, slips over the vent stack and automatically adjusts to pipe size and roof angle. Won't rust or corrode. No roof discoloration.