Sammons Preston Reusable Hot/Cold Pack, 8-1/2" x 11", Blue, Safe, Nontoxic, Latex-freeTransparent blue hot/cold pack can be microwaved, boiled or placed inFreezer. Unique fluid center does notFreeze solid, even at temperatures below 32°F. Safe, nontoxic, noncaustic and biodegradable compress can be used over and over. Makes an excellent pressure ice pack when used with elastic bandage