Went on a search today for a spirit level small enough for my EQ6 mount Tripod today.
I found this perfect item at Home Hardware. It is a round spirit level measuring 35mm across, so it completely covers the central hole. It works a treat and only cost $7
Heaps bigger and more accurate than the ones they supply with the tripods.
It is an
'Empire' Bullseye Circular Level. Item number 3604
On the back of the packet it says for Cameras & Pool Tables.
Sorry for the bad pic but I don't have Macro.