Harbor Freight Tool

There is one tool from harbour frieght I would like to have.It is for vacuuming out the AC system,via your compressor. It's a little item less than $20,just never got around to it. When I work up to it I plan on having the system drained by a pro. He owes me a freebie. I'll make the repairs,vacuum the system down and wait overnight for really good drainage.Fill it myself! Should be gold after that.

This one...

http://www.harborfreight.com/air-vacuum-pump-with-r134a-and-r12-connectors-96677.html

My point being,has anyone bought one of those? Got a review for me?