The stud chain is often used on intact male bio-equines as part of the halter when the animal is "spirited". While, I have used it in the bio-equine world, I have not used it nor have had it used on me during ponyplay. I know it's possible to use this in ponyplay, but all of the ways in which it is applied to a bio-equine just look like a recipe for trouble if applied similarly to a human especially if you have dental work. So, while I personally do not use this, I will briefly describe how it is used on bio-equines, and you can decide for yourself if you want to give it a try. Here is a stud chain:
The stud chain is applied to the halter in one of four ways: