Looks like I'll be ordering some myself. Wen to measure and the clear dome part came right off the sticker part.
But the measurement came in right at 40mm.
Edit: Looks like there
ARE 2 different sizes available on Ebay. The larger (one you got purplecty) comes in a set of 4 and the smaller comes in a set of 6. I just ordered the set of 6 so if you 2 want in we could all have 2... or if just one of you wants in we could have 3. Cost was ~$22. They are coming in from Latvia so plenty of time to decide.