Black Silicone Bulb Type Gasket Weatherstrip, T-Slot Slide in bulb weatherstripping used on windows and doors. This bulb silicone gasket would make a good seal for many different sealing and gasketing requirements, as well as to cushion, edge and insulate. Color: Black Material: Silicone Bulb Width: 3/8" Backing Width: 7/32" Length: 20 Ft.