Generation IV External Engine - Aftermarket belt tensioners vs. Katech

Can someone tell me what exactly is the difference between the Katech serpentine tensioner and this one?

Click Here (http://www.ebay.com/itm/LS1-Ultimate-3-BOLT-Tensioner-With-Pulley-/221023494890?pt=Race_Car_Parts&hash=item337606e2ea&vxp=mtr)

I'm looking to buy one for my LS2 GTO and saw this one on Ebay.

Thanks

it uses three points. most only use two .