Standard Non-Insulated Hot/Cold Versatile Gel Packs are for therapeutic relief of muscle aches or pains. ColdStar Hot or Cold Therapy Packs maintain an even temperature over the entire pack. ColdStar Hot or Cold Therapy Packs are the highest quality! ColdStar Hot or Cold Therapy Packs are leak-proof and contain no liquids or dyes. ColdStar Hot or Cold Therapy is biodegradable and contains only non-toxic ingredients.