CO guardian
I bought one of the portable units at OSH '05. It was a show special, listed as $20.00 less than normal price. I have not noticed any problems with the unit and it appears to function.
My only problem is that when I got home from the show and the charge showed up on my credit card, the guy had added a $20 "service charge" to the price, wiping out the show special "buy". Now, this service charge was not mentioned anywhere on his display at OSH, nor on the receipt. I disputed it with the cc company and ended up only paying the show special. I have a hard time trusting this guy, obviously.