u/That1GuyFromATL

I bought this weight from Amazon and it’s 45 mm. I could maybe go down slightly to 43/42 but if I want to upgrade to a different style weight from the chaingang do these numbers convert over exactly? Or if I order a 42 from chaingang, is it going to fall off me? I ordered this same style in 40 (couldn’t get it on but maybe because I was so new) and in a 50 and it fell off once I moved around. I can work out in this 45, running, jump rope, etc and it stays on, but I wouldn’t be adverse to it being a little tighter. Thoughts?