Found all sort of information on the 310, but nothing on the 312 model. They look absolutely identical in pictures down to the ball bearings in plastic retainers, Just the model number. Why did Mavic even bother to call it a different model number then? Any Mavic experts here know? The Mavic hedaset model lists I have found so far seems to jump straight from the 310 to the 315 without any mention of the 312.
Here's pics of my recently aquired "mystery" 312 mode for referencel:
It definiteyl says "312" on the plastic cyclindrical container it came in.