SP rings come in a range of sizes and prices as in the size table below.

For birds smaller than cockatiels the plastic split rings are a slightly different design, going aroiund the leg only once and relying on the strength of the plastic to act as a spring to hold the ring in shape. The are put onto the leg with an applicator (supplied with the rings) which simply opens the ring up so you can lie the birds leg inside it. You then slide the applicator oput and the rings clses around the birds leg. To removes just reverse the process..

Ring sizes and prices