Lawn rake/thatch remover

Hi I hope my description is good enough, but I am looking for a rake that I saw ages ago on Gardeners world on a segment about lawns and removing thatch etc...

It is an old style rake I think at least I dont seem to be able to find a modern equivalent, where to start with the descripion??

The action it uses is a push and pull action, as you push the rake the blade like hooks flip/rotate under and glide over the grass as you pull the rake toward you they flip/rotate back out toward the grass and rake the moss and thatch out.

and it made for a very efficiant looking action.

Just wondered if anyone had seen one or knew where I may get hold of one (sorry not a great decription).

If I find the clip or a picture I will post it.

Thanks for looking, James.