I assume that we are talking about a pressurized cannister that feeds fluid into the MC under low preesure so brakes or clutch van be bled single handedly?

If that is correct, I have one that i got from Holden, it works great as far as I am concerned. The only real trouble is sealing the connection to the master cylinder. I have cobbed up a bunch of odd looking contraptions to accomplish this. Sometimes I have to tie this adapter down with bailing wire to keep it from blowing out like a whale exhaling.

Very low pressure is one key to success, as low as 5 pounds or even less seems to be enough to get results. I use a portable air storage tank with a small compressor regulator to feed air into my bleeder.

I'd never go back to throwing myself on the mercy of unwilling assistants if I don't have to.