The "standard" MKS EZY work like a hose quick-release: pulling back on the collar allows 4 small balls to retract into the housing, allowing the pedal shaft to be removed. A spring returns the collar to its original position.

There were reports of the pedals spontaneously disconnecting. MKS furnishes a pair of plastic "C" clips with the pedals which, if placed properly, prevent the collars from being pulled back inadvertently. It was never clear how the pedals released themselves... I suspect the rider's foot somehow managed to retract the collar. I have never (as in "not once") had this problem in over 20,000 miles with these pedals without using the "C" clips.

There must have been something to it, though, because MKS subsequently came out with the "EZY Superior" line, which have a pull-and-twist collar mechanism. Now I see there is a new "Always Superior" line (see Thor's site: Pedals and Shocks).

More than you wanted to know, maybe...
Steve