An oval chastity base ring has exactly the same inside diameter as the round ring it’s ordered as. We make the round ring first, in your size, then shape it slightly oval, wider than it is tall. So the shape changes how the ring sits against the body, but not what size you order or how you find that size: the round plastic sizing rings fully size an oval order, and there’s no oval test ring because none is needed.
That single fact answers most of the questions we get about ovals, and it’s the reason this article exists: nowhere else online explains it, and the confusion sends people looking for measurement methods that don’t exist. Here’s the ring, the shape, the sizing, and how to choose.
The base ring is the part of a chastity device that sits behind the testicles. The cage locks onto it in front, with a gap between them, and the testicles sit outside the device in that gap. They can’t pass between cage and ring, so the device can’t come off. The ring, then, is doing only one thing: holding the cage up.
Its size is one of your four order sizes: cage inside diameter, base ring inside diameter, length, gap. The right base ring is tight enough to hold up the cage and loose enough to allow blood flow. In practice that means, at your normal flaccid state, exactly one finger fits under the top of the ring to the first knuckle without forcing, slightly snug. Two fingers is a size too big; none is too small.
Everything above is true whether the ring is round or oval.
Oval base rings have the exact same inside diameter as round. The ring you order, say a size found with the sizing kit, is made round first. It’s then shaped slightly oval: wider than it is tall. Nothing is added or removed; the exact same size, just reshaped.
Because it starts as the round ring in your size, an oval order needs no special measurement. The plastic sizing rings are round, and they fully size an oval order. A customer once wished, in a review, that there were a way to test the oval shape in advance; the answer is that the round ring you tested is the oval ring you’ll receive, before shaping. No oval test ring exists or is needed.
When you put a round ring on a round cage the gap between the ring and the cage diagonally will always be bigger at the bottom. When the ring is wider than it is tall it will have more of an even gap diagonally all the way around the cage. For many clients it adds to the comfort and security.
What the shape does not change:
Oval is an option offered on our custom devices at order time at no extra charge; the Jail Bird spec sheet lists shape as Round or Oval alongside the four sizes.
A few practical notes on the choice:
If a ring is letting a testicle slip or the cage is sagging, that’s a size question before it’s a shape question; our ring-size fix piece covers it, and the full sizing guide has all four sizes.
Locking cock rings are sometimes worn on their own as a symbolic or day-to-day ring. We’ll cover locking cock ring wear in its own article later in the series. The sizing rules don’t change for the base ring: but will change for the inside diameter of the cock ring. Our types guide sets out where the ring sits in the anatomy of every design.
Whichever shape you end up ordering, the size comes from the same place: the plastic sizing rings, worn for at least a week. Get that number right and the oval question becomes a preference you can decide calmly. If you’d like our view for your anatomy, email the workshop with your four sizes.
