The Manhole Gasket GSK-763C036H21 is an industrial seal designed for use in boiler tanks. This tankless water heater/boiler unit is manufactured in the United States and includes one gasket. Its model number is GSK-763C036H21, making it a specific and reliable option for sealing manholes in industrial settings. This product falls under the category of home improvement, particularly in the heating, cooling & air section, making it essential for various utility applications.