∨ DESCRIPTION DonJoy Kid's Marvel Reusable Cold Pack. The Kid's Reusable Cold Pack is intended to treat muscle pain, joint pain and swelling with cold therapy. This round ice pack measures at 5 7/8in diameter, the perfect size for children! Designed to remain flexible even after freezing. The cold pack will remain cold for roughly 30 minutes. Kid's of all ages will love the fun and unique Marvel designs available. Choose from Spider Man, Captain America or The Hulk!