The Cryo/Cuff has a wrap-around part like a blood-pressure cuff and a container holding iced water. When the container is lifted up water circulates via a tube through the cuff and keeps the knee at a constant temperature.
As the cuff fills with water it provides controlled compression around the knee joint and this has been shown to be highly beneficial, especially in the treatment of acute soft tissue injuries.
Other benefits of using a system such as the Cryo/Cuff is that the ice and water is all contained so you don't have iced water leaking everywhere. Plus as the ice is kept in the container the risk of getting 'freezer burn' on the skin is reduced.
Although the units are significantly more costly compared to a bag of frozen peas if you need to ice your knee on a regular basis they are much more convenient and comfortable.
The cuffs come in various sizes so if you are thinking of purchasing one make sure you get the right size for your knee.
Sizing chart information - Leg Circumference 6" (15 cm) above the patella
Small Knee Cuff - 10"-19" (25-48 cm)
Medium Knee Cuff - 18"-23" (46-58 cm)
Large Knee Cuff - 20-31" (51-79 cm)