Well designed and comfortable size.
This O-ring is a great product, eminently usable and the silicone coating on the ring makes it easier to wear for longer periods. It has a slightly smaller opening, meaning it won't suit all players equally. In this case, it is great for simply teaching someone not to drool at the sight of something delicious. The packaging is good enough, and the collar itself is adjustable so it fits a variety of sizes and is fine to be worn for quite a while without discomfort. Overall, I highly recommend this but do think about how big an opening you might require to make full use of said opening. Only drawback is the silicone is vulnerable to bitemarks. These may just add to to the experience however