Yeah I looked into those, but in practice it seemed easier to just get a 5lb propane tank for camping that I get refilled at the same place I fill my 20lb tanks

Yeah I looked into those, but in practice it seemed easier to just get a 5lb propane tank for camping that I get refilled at the same place I fill my 20lb tanks. (Plus I'm not clear about the legality of the Flame King ones in Canada, with the result that there aren't any reputable sellers.) If I really need to go light I'm carrying isobutane canisters or using an alcohol stove.