Small -- Fits 7" to 8-1/4" Ankle and 11-1/2"to 13-1/2" Calf
Medium -- Fits 8-1/4" to 9-1/2" Ankle and 13-1/4" to 16" Calf
Large -- Fits 9-1/2" to 10-3/4" Ankle and 15-3/4" to 18-1/4" Calf
Extra Large -- Fits 10-1/2" to 12" Ankle and 18" to 21-1/4" Calf
2XL -- Fits 12" to 13" Ankle and 19" to 22" Calf
3XL -- Fits 13" to 14-1/4" Ankle and 19-3/4" to 23" Calf
4XL -- Fits 14" to 15-1/4" Ankle and 20-3/4" to 23-3/4" Calf