Five different pin arrangements for MR16 lamps MR = multiple faceted reflector and 16 refers to the diameter of the front of the lamp.
(a) 2-pin
(b) medium screwbase with integral transformer
(c) intermediate screwbase with integral transformer
(d) turn and lock
(e) bayonet
copied from HERE
Good find. But the suggestion that MR16 lamps are only available below120V is clearly wrong or perhaps out of date.