These are the same Rapid Phase Change Material packs as supplied with the RPCM vest (Part No. 2765). They contain all natural ingredients, with no hazardous chemicals. They will not harm you if the packs become compromised and the contents spill or get on your skin.
No freezer is needed with these cold packs. Simply drop them in a cooler of ice water for about 20 minutes. The bio-based cooling packs remain at a cool (not cold) 59° F for up to 2.5 hours. One set of packs completes one RPCM vest. A spare set of packs lets you rotate for all-day comfort.