Barlow for Negative Projection astrophotography

[Albireo380]

I have a cheapie 2xBarlow that I have been using for negative projection astrophoto's. It has a thread that fits the T mount for my DSLR. I would like to get a much better Barlow, but am not sure which would be best for this purpose.

I would like one with a built in thread, as this makes it easy to attach to the camera body via the T mount. I don't have any astro dealers near by, so can't pop in to a shop and browse. On the net, I see lots of nice, shiny Barlows, but don't ever see a thread on them, or read in the blurb that the thread is integral to the Barlow.

1. Do most Barlows have an integral thread - for attachment to a T Mount? If not, can anyone recommend a good Barlow that does?

2. Is there another method (some sort of attachment??) that I can use to mate the Barlow to the T mount and thus to the camera body?

Advice please - I don't want to buy a Barlow for astro negative projection, unless I can attach it to my DSLR.

Awaiting enlightenment

Tom