Can't find a good ring size for my vice

I had to look that one up.... So, looking at it, if you've got a ring that fits right, and you lose circulation, go with a bigger spacer. The picture on Amazon has a really tiny gap (6,5mm), which would do the same thing to me with a proper sized ring. Move up to the bigger spacers, and they'll constrict less skin, restoring circulation (hopefully, right?) . Don't go so big that you're popping balls out though - it's a delicate balance

 

So, the second result on google search for vice mini chastity leads to amazon

https://www.amazon.com/Locked-In-Lust-Vice-Mini/dp/B078XNQ971

That has the following section

-- Spacer/Pin Gap (Ring Distance From Cage) --

Small - 6.5 mm
Medium - 10 mm
Large - 13 mm
Extra Large - 15 mm

I tried a 6.5 (with a different cage), and with the right size ring, I was not getting proper circulation. With the bigger ring, circulation was fine, but it was slipping... unfortunately that one does not have adjustable gap (it's the only one I didn't make myself), but now I know what my preferred measurements are.

 

I am having a similar problem. The 40mm ring starts to hurt pretty quickly. The 44mm seems the best. It is uncomfortable but I think I will get used to it. It seems completely impossible to remove because it is so tight. I find however that after 12 to 24 hours something happens and the ring starts to slip off and with a very slight pull come off completely, anti pull out and all. Some how one of the balls receded by itself and gave enough room for the device to slip off. As I said the 44mm was super tight at the beginning. Is it possible I just need a different spacer???

 

Yes, if the base ring is the right diameter, then the gap between the ring and the shaft cage needs to be smaller to provide less space than a testicle would need to get through there.