Its a cross between an ATS and a salisbury conventional slipper.
It is supossed to run free on the over-run (when not being driven)
and lock and work like a plate diff when under power.

Don't know if you would gain much for road use as you would set the plates at a low pressure.
For circuit racing they can be an advantage as you can run the diff well torqued up for driving out of the corners, but it won't give you a massive understeer going into the corner.