I picked this up along with an extra for my Prusa i3 Mk3s, thinking it was a genuine Gates Power Grip GT belt. The Gates Power Grip GT belts are the ones that are included with the Prusa kit.
Unfortunately, these belts are not labeled as Gates Power Grip GT. There is nothing branded on them at all. They fit on my printer and seem to be working, but it's difficult to say what the quality of these will be like over time. My original belts lasted for 3 years with almost non-stop ABS printing in an enclosure. Will update this review once I've had time to break these in.