A brake lock differential/ELSD is a system on modern 4wd vehicles that can make an open differential act like a locked one when needed If one tire is slipping and one is stopped (one tire on ice and one on road) the system will apply brake to the stuck/slipping wheel forcing the power to be transfered to the other wheel this is not a locked differential because the wheels are not always spinning together permanently but only when there is slip the system will activate
All our ESC/TC equipped cars already have that to varying extends (depending on drivetrain configuration etc)
ah ok I thought it wasn't there because when I went off road in the etk it did not seem to do that I guess the etk just does not have that feature