Here's what Omnium has to say:

Sometimes when it gets HOT and HEAVY and you are delivering regular elephants each and every day, then the front headset can get loosey goosey. Normally it never happens, but this locking love-ring is for that time when it does.

• • • Integrated version is for new models of Cargo and Mini-Max, where the bearings sit inside the headtube.
    • Non-integrated version is for old models of Cargo and Mini-Max, where the bearings sit in an external cup.