Tension Rings for use with traditional Vacuum Therapy Devices. Buy 3 and get 1 free. These rings are not used with the Vacurect, Vacuum Therapy Device. Traditional Tension Rings include, Ultimate I (Left), Comfort 12.5, 15 (Middle), and Loop 4, 5 (Right). Please indicate which rings you would like to purchase in the "Comment" field. $12.99 each if purchased separately.