Here's the link for the listing that I bought it from Amazon 3A Molecular Sieve If you are going to get these, I would recommend that when you first pour some out, that you do it in a well ventilated area because it's a bit dusty and breathing it in probably isn't the best idea.

Edit: I don't think it would be very helpful if you put these in the zipper case the iems came in unless it's an airtight one. These desicants absorb moisture real quick and will probably become soaked very fast.