My pocket chainsaw resembles the one you got at Walmart, its called a SaberCut from Ultimate Survival, a good brand that makes fire sparkers and other interesting things, http://www.ultimatesurvival.com/product_view.cfm?product_ID=430. I originally bought it thinking to replace my Sven saw for cutting away smallish trees down across the trail (while I don't cut green branches for shelter, I do cut the occasional dead tree to clear a trail :-)), and its pretty good, but I think the motion of sawing with the Sven saw is more natural, I've kept it instead. Now the SaberCut is relegated to a BOB, but its not clear why I would use it in an emergency (most of the trees that might fall around my house are too big to cut by hand). Its definitely smaller and lighter than a Sven, and seems plenty durable unlike imitators, just not quite as handy as a Sven or frame saw.