This is the one that I use. http://www.grizzly.com/products/30-G...eparator/W1049

I fits on top of a trashcan. I think that I loose a little power but it does the job. Not sure that it was absolutely necessary but I did run and connect my ground wire inside of the trash can. I still have to empty my bag on the dc but not nearly as often. Its a lot easier to carry out the trashcan than remove the bag.