Opsak home > Opsak « back Along with being 100% water/air tight like our ALOKSAK, the OPSAK (Odour Proof SAK) is also a 100% odour barrier bag. We use the same seal on our OPSAK – no gusset – that we use on our ALOKSAK, but with a different film that is odour proof and FDA approved. You can store food undetected to animals and other pests in your campsite by sealing them in the OPSAK.