aLOKSAK OPSAK Waterproof Storage Poly 9" x 10" - Odor Barrier Bags Along with being 100% water/air tight like our ALOKSAK, the O.P.SAK (Odor Proof SAK) is also a 100% odor 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 odor proof and FDA approved.