Powermate does it require an extension?

I have been reading about powermates vs barlows and I'm still a bit unclear of the practical difference.
Does the use of the powermate eliminate the need for the use of an extension tube to achieve focus?

I have 2.5x and 5x Tele Vue Powermates (1.25 in) that do just fine in a TV85 without the need to use an extension. Their use is a simple matter of placing the Powermate between the eyepiece and diagonal, and refocusing as required. But an extension is not necessary to achieve focus.

Hi Bill,

I've used the 2.5x Powermate successfully with a 5" and 8" SCT with no issues. I also have the TV 2x Barlow. On any given night I always check with both for the best results when observing double stars. I have not tried to correlate conditions to performance.

Pete