those fittings that have a flange or collar that you slide back to release? in our neck of the woods they are called 'quick disconnect' or 'quick release' couplers.

if you have one that is leaking fluid look on the inside of the female side, you will see an o-ring, they wear out or get cut, you can usually just replace the o-ring and that will fix the leak. I believe they are metric also ;o)

hope this helps