let me say first that I tried to search info into this sub-forum before posting but all my keywords (like base ring, sizing ring) have been rejected because too common

I want to upgrade from a Holy Trainer v2 Small with ring diameter of 45mm to a MCN Contender.
My sizing principle is: take the smallest diameter that is comfortable to wear for 24h/48h.
Methods known:
Chastity sizing rings. I know other shops sell these rings (not MCN) but I want to keep this as last option.
Comparison with the HTv2. Not possible as the 2 cages are totally different.
Thread method. When I bought the HTv2 I measured myself using this simple technique (wrapping my scrotum with an inelastic thread or shoe lace until a tight fit is achieved and then measure its length). It kind of worked, however I believe it is inappropriate for a custom metal device.
Plumbing metal/plastic rings. Mark from MCN has suggested to look for these in the DIY stores, which I did with no results (I'm not in USA or Europe and DIY here is not a big thing).
Jubilee Clip. This is the closest thing to a sizing ring I found in mt DIY store. It is obviously thinner and wider than a MCN ring, it would probably be more representative for a CB6000 ring, however it might do the trick: I was thinking to factor for the increased width (it is ~6mm wide) ordering a MCN base ring one size smaller than the size measured with the clip.
What do you think about the jubilee clip method? Any other idea from the chastity masters in here?
