DetailsZoot Calf Sleeves Size Chart Want the secret to fresher feeling calfs? The key is Zoot's Ultra 2.0 CRx Calf Sleeves. Graduated muscle-specific zones of compression to stabilize muscles, reduce damage during exercise, and improve performance. NEW Lighter weight yarn transports moisture away from the skin spreading quickly and drying faster. Experience the benefits yourself with the Zoot Ultra 2.0 CRx Calf Sleeves.