http://www.biorelief.com/products/portable-toilets.htm
I needed to order a back up device and well the site I previously used I couldn't find and in fact the last time I ordered from them they didn't have the product I wanted.
I found the above site that had a selection of items I have tried and haven't tried and I thought I'd pass it along.
I've use the travel mate ... it's okay
I really have liked the whiz. Only once had a mishap and that really was my fault and not the products ... otherwise it's pretty effortless. My current one is even a little deformed from bending it and it still works great.
I also ordered the go girl this time. I like the fact i can get a non pink/purple version!