I was discouraged by the price TST was charging for a package of 6 replacement O-rings for their TPMS.
To be fair there's other stuff in there, tiny screws, gasket for the Schrader valve, but in general you're buying it for the 6 O-rings when you replace the batteries.
Don't get me wrong, I love the TST TPMS, but $9 for the O-ring set AND $11 to mail it baked my bagel.
So in the interest of science, ahem, I bought the set from TechnoRV, and after reading several forums determined that the
O-rings are 11 mm. x 1 mm. Amazon has a package of 100 for $8 with free shipping.
When they arrived, I photographed the two packages with a sample of each. The TST is on the left, China O-rings on the right. You be the judge.
BTW, I have the cap sensors so I can't swear the flow thru are the same.