RTV silicon for fixing ports to mushroom cultivation lids

Brand my vary.

Red Hi-Temp RTV is specially formulated for high temperature applications. Withstands temperatures from -56ºC up to 315ºC (-70ºF up to 600ºF) continuous and up to 343ºC (650ºF) intermittent. Resists high pressures to 5,000 psi. Dries flexible. Resists shrinking and cracking.