Permobond® RS-5620 Black Bromobutyl Rubber Protective Rubber Lining allows thesame workability as other butyl linings but exhibits stronger physical characteristics than the other butyl counterparts. The RS-5620 comes with an optional proprietary bonding layer for added adhesion. he RS bonding layer also will give the same service condition resistance as the face stock. The 5620 can handle constant temperatures of 260°F (127°C) with temperature spikes to 310 °F (154°C). FDA Complaint per 21CFR177.2600.