KO (Knock off) its a pirated or illegal duplication by other manufacturing on the original toys. Usually they will try to make certain changes such as color, size and the packaging. But some KO duplicate the whole set as it is.

Most of the time, their quality its bit low compare to the original item, but some does have a very good quality. And most of them are from China!

Here its some of the item I have sighted, and next time I will have more details such as price and location.

Undersize Victory LioKaiser

Transformers ROFT & DOTM

Oversize Bumblebee

Oversize Optimus Prime

Others