PxHD is one of the most unique trackers in the world. What they offer is exclusivity because you won't find their encodes anywhere. In addition to their classic 720p and 1080p encodes, they also encode 2160p in mp4 and mkv containers.

Internal categories
PxHD -720p and 1080p
PxHDA - which includes DTS audio and Higher video bitrate
Px4K - 2160p with DOVi and HDR10+