This stainless steel infinity collar has one section (a quarter of the circumference) which pops out by use of a key. The collar can then be slipped over the neck and the collar closed. All that is visible is the key hole on the bottom of the collar and the two seams where the section fits back together with the rest of the collar. Ring at front. Inside diameter measures 5-3/8", collar itself is 3/8" diameter. Weighs 10oz.
Includes one key. Note that the key is a generic key, and not keyed to a lock. The key is used to trigger the spring release mechanism.