Simply put, Silicone is the only premium material for an eco-conscious koozie. No animal hides or petroleum products here. Just plentiful and easily sourced elements. Silicone can withstand temperatures from below-zero to over 400ºF, is non-toxic and contains no BPA. It can be microwaved. It can be dishwashed. It can be dropped. It can be baked in the oven. It can be thrown off a tall building or from a moving car (although you may have to replace the mason jar inside).