Not a PR860, (the PR860 is a professional series radio which resembles the ht series). Not the PR1500 (this radio, while it might closely resemble it, the purple side button is smaller and round not like the one in the pic). That brings it down to 3 other radios. The MT1500, XTS1500, and XTS2500. Now this is where the issue starts, all three of these radios have the same looking front covers, except for the older MT1500's which had a grey cover. To know the exact model of this radio you need a good view of the front label of the radio. As for the knob, it's a replacement one. The XTS1500\2500 rebanded models come with that type of knob along with the regular one (and I know this radio isn't a rebanded model).