Blackburn Airstik SL is very light (58g), and fits in seat bag easily. Takes a while to reach 100 pounds plus, but it does work. Makes a good emergency backup to a C02 cartridge.
__________________
You could fall off a cliff and die.
You could get lost and die.
You could hit a tree and die.
OR YOU COULD STAY HOME AND FALL OFF THE COUCH AND DIE.