NB: Picture shows prototype, actual product is a very sexy black-anodised aluminium and now includes a compass! 

All those EQ mounts out there with no leveling bubbles!  You level the tripod... then when you drop the mount on - pooof!  There goes your careful leveling! 

Designed for the HEQ5 and EQ6 (after a particularly nasty polar-align session at Kelling this year) but will fit most mounts.