This is a replacement O-ring door seal for the Fast Access ISO 100 Blind Entry Door Without Window. It is used on both the ISO-K 100 and ISO-F 100 blind doors. This seal is field replaceable.

Check the O-ring door seal regularly to make sure it doesn't leak and is still pliable and not permanently deformed. Replace the seal as needed. Its always a good idea to keep a spare on hand.