Instruct: Classify the given Amazon review into its appropriate rating category
Query: DO NOT sous vide

I love these silicone packs. I feel good knowing they are inert BUT the closure is not. If you sous vide (and maybe boil or microwave), the plastic sealer warps and who knows what is off-gassed. The sealer is ruined at that point. It's warped, bent and totally unusable. Freezing and storage A+. Sous vide or boiling, F-.