If you go Powermate you’ll also want the T-ring adapters when imaging. These replace the visual top half of the Powermate to ensure correct spacing.
See
https://www.televue.com/engine/TV3b_...id=53&Tab=_acc
Note there are different models for different Powermates.
Note also the 2.5x as pictured on the Tele Vue web site has the longer full diameter barrel presumably threaded for 1.25” filters (never seen a picture of the new one from below). The older and original Powermate as pictured on the Bintel web site (and many foreign vendors) has a stepped barrel and is not threaded for 1.25” filters. (I can confirm this as I have one).