I recently purchased Henntec for M1A2.
My understanding of tensioner is that when you drive your tank to uneven surface, the tensioner would stretch the tracks back and forth from Idler to prevent from track slipping off the sprocket.
I haven't install the tensioner yet. But i couldnt see it how it supposed to work apart from adjusting the tensioner position to stretch the idler to suit your preference to stop the track slippage.
Is this correct?

I mean more like this kinda tensioner im referring to: