Scotch Rubber Mastic Tape 2228 is a 65-mil thick, premium grade, highly conformable self-fusing rubber electrical insulating and sealing tape.Scotch Rubber Mastic Tape 2228 consisting of an ethylene propylene rubber (EPR) backing coated with an aggressive, temperature-stable mastic adhesive on a liner. Designed for electrical insulating and moisture sealing, intended for both indoor and weather exposed outdoor applications including resistance to UV exposure.