I bought one of the commercial grade ones about ten years ago.....great for bait keeping. As the deteriation process requires air to take place it certatinly helps keep bait from rotting for quit a while, compared to just in a bag, also as Bet has mentioned it prevents freezer burn.
Another use I've found is for adding bait soaks......put the bait in the bag, add your soak and then seal. As the air is drawn out of the bag it is also drawn out of the bait and the soak gets drawn into it. Allows you to use less of the soak as it spreads out better.
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