McKesson Cold Compress - Instant Ice Pack for Minor Injuries, 5 in x 7 in, 1 Count, 24 Packs, 24 Total

Affordable, easy to use. There's a small bag of chemical salts inside the larger pouch of water. I see some people may have difficult breaking the inner pouch. Fear not, you won't break the thicker outer pouch. The inner bag is very thin plastic. These disposable ice packs from McKesson are very good quality offering immediate and relatively long lasting relief. Just an FYI for disposal: cut open the pouch and drain the solution in a can allowing it to evaporate or pour into general trash. Recycle the plastic bags. Don't dump the solution down the drain as it will congeal and clog. It's also not appropriate for the compost pile. Anyway, this is a good product to have in your kit. I keep a few in my car as well.