A must-have accessory for Terra Firma and other harness users who like to play with dildos of varying sizes. Make sure that the small ones don't slip out of the harness or that the large won't break at the base. Pick a ring that fits just right. This pack of black rubber O-rings includes one each of: 1-1/4", 1-1/2", 1-3/4", and 2" rings. Sorry, not sold separately.