Tuxing Gold Filter - O-Ring Size

Does anyone know offhand the size of the o-rings used on the end caps of the Tuxing gold filter? Yeah I know there are folks all over AliExpress selling two for just over $7 but I figured on picking up maybe 20. I found more economical sources but the size is a concern. The best I can tell the o-rings are either 40mm or 41mm OD with a wire size of 2.5mm.
 
I have a gold filter but under a different brand called "Xin Yong Shi" . The dimension of the green O ring is 2.5 mm section x 38 mm OD. The Oring has a snug fit with the seat at the end of the aluminium tube so you just need to measure the diameter of the seat with a caliper to determine the OD. 

The material of the O ring is a bit soft and everytime I open up the filter, I saw fine filaments of O ring material spread around the seat. I believe it was caused by the O ring being cut when the high pressure squeezes it into the gap to be sealed . However, there has not been any failure or leakage after a year and I still have got two spares that came with the filter so I think it will be good for quite some time to come.
 
I think if the material is too soft the pressure just deforms it. I've had two blow out of the threaded body. I had a similar experience with the Huma regulator O-rings being too soft and the pressure would push them out of their groove. I increased the hardness from 70 to 90 and that solved that issue as well.

JK

I have found the same thing. The original green ones are only suitable for single use. They deform and expand after being pressurised. If you try to reuse them, they may pinch preventing the cap from butting properly against the housing. Even a couple of thou. gap there will allow a blowout. I find it a good idea to replace the O-ring each time it's dismantled. A fine smear of silicone grease helps prevent pinching and aids seating the two surfaces with zero gaps.
 
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