Three blue ones came with my LMGT1, so I can measure those if you wish. But I'm pretty certain they're just the regular old style RAYS caps.
I'm sure you'd have no trouble moving 50 units (I'd be down for one lol).
As above, factory gauge is 'normalised', that's why it jumps to the middle quickly and stays there until your engine's very hot, kind of useless to us but keeps the "general public" drivers a bit less worried.