The Liberty Mountain Loksak OPSak Odour Proof Barrier Bags 3‑Pack Help ward off animal campsite intrusions by storing food and other items in these durable, resealable odour barrier bags. Odor proof bags to use for food storage. OPSAK bags are re-sealable and proven to be odor-proof. Whether you are camping, traveling with a baby or adventure racing, these light-weight storage bags will make for a safer, more pleasant journey. OPSAK is rated as a biohazard containment bag by the US Government.