Reddit mentions of Locking Chastity Cage Rikers w/ 3 different sized Cock Rings . Made in US . Kinky

Do it! Some of the experts in /r/chastity might have more advice, but I'll tell you what I can.

I'm self-locked. Partnered, but he recognizes that being locked is my turn-on, so it works well. The ring is loose enough that I can pull out if I'm soft (though I don't) -- this maybe isn't how everyone chooses to do it, but this way I can clean off in the shower and re-lubricate (which is really important for comfort, especially when it comes to sleeping).

I don't do anal a lot, mostly just prostate stimulation when I get really frustrated, and even that's not really release, just feels like more teasing.

Here's the device I have -- not sure why it's so expensive now, it was about $20 when I bought it a couple years ago. If you want an equivalent, just search for CB6000S -- they carry them on ebay and DHGate and I'm sure other sites. If you're just starting out, a cheap device is what most people recommend just to see what works and what doesn't for you. I had to go through a few different devices, including a larger metal one and a larger silicone one, before I found that a smaller CB device is actually really comfortable and doesn't make too much of a bulge down there. This is another one I have and like a lot. People in /r/chastity can probably give you some more advice about measuring for fit -- what I can say is I'm about 7" when fully erect and the CB6000S fits me well (probably better than the longer version of the CB -- it's counterintuitive, but smaller cages tend to be more comfortable, and here's why: if a cage fits you snugly when you're soft, there's not as much room to slide around in it when soft and have bits of skin or the head catching here and there, which makes it hurt when you get hard). I also like to be able to piss standing up, and using the shorter CB makes that a lot easier -- once you're locked, you'll see what I mean. As for ring size, ideally what you want is something secure but not too constrictive when you're hard (if you have discoloration or numbness, it's probably too tight).

That metal one was my first, it is awful. The post on the base ring is too long, so that when you lock it through the post, the main cage's two prongs can still unseat from the ring, and it can rotate, which most often leads to some really shitty pinching. Or best case scenario, it's easy to get out of. I improvised by zip-tying it, which works but sucks.
Wound up getting the Riker's Master Series, which has been great. They are like $20 on ebay.
http://www.amazon.com/Locking-Chastity-Rikers-Master-different/dp/B00VF3SV20/ref=sr_1_1?s=hpc&ie=UTF8&qid=1453428040&sr=1-1&keywords=Riker%27s+cage