A while ago this came up in a thread. I lost mine I bought in MN and I haven't ever seen them in Canada. UNTIL NOW! Basspro has a whole pail full of them near the ice shacks. So I picked up two. These are awesome for keeping things thawed or frozen. Excellent for maggots and meal worms or keeping you velvetta cheese froze!
Example of what I'm taking about
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Bait Pucks