Has anyone tried one of these yet?

Looks interesting. I like the design of the lock

 

The lock is complete rubbish. Makes one very vulnerable to pinching the skin with severe pain ensuing. I have actually purchased one of these devices, and they're not terrible. But I would recommend stuffing something soft (like part of a tissue or something) within the gap where the cage joins up. This way, it makes it like any conventional device where you shove them through, instead of risking nerve injuries/damage as a result of poor timing when closing the device.

There are a few of these devices with openable rings on the market, and it was a poor choice in my opinion.

Other than that, it caused no real trouble/discomfort at all from what I noticed.