Definitely my favorite metal Primal ring, having tried all of them. I do think Energy's harder edges are a bit more visually appealing, but Fusion's rounded edges are much more comfortable for extended wear, and it still retains a bit of the weight and heft compared to Spark. The matte finish also looks very nice under all conditions, which is a nice touch. I've really got nothing bad to say about this thing, it's the best of the best.

It also works very well at enhancing my cock of course, but all of the rings sold here do ;)
Getting 5mm down from my normal round size of 45mm (so 40mm Primal size) fits tight but not uncomfortably so. I can and do enjoy wearing it all day without any issues, and have not once had any issues removing it despite how strong and durable it makes my erection.
If you want a ring and aren't sure which to pick, GET THIS ONE.

This is the first metal cock ring I have gotten. I am not entirely certain I have the right size but it is comfortable.

I went with the 45mm even though most of mine are 50mm. It’s nice and snug, definitely feels amazing and does its job, but it’s also not a ring to wear 24/7. I can tell when the sensation becomes too much. Pay heed to the caution. Don’t wear this for more than 30mins to an hour.

I bought the fusion in a 45mm. I usually wear a 47mm round which works flaccid and erected. But this 45 works all around will probably be more 24/7 wear. The weight is exciting on its own.

Sexy piece of hardware! Fits awesome and makes you rock hard- partner loved it too. Get one!