The right size at the right price. Most of the projects I take on end up with a lot of material being left over as scrap or just lying around until you lose or ruin it. It took me little to install a gas line to my new gas magazines as my old bottle was as obsolete as many times before. So I order a tube instead of a regular bottle, save $10 and have some left over. Do yourself a favor, you're doing it for yourself! Only buy small tubes so you don't have to throw away as many as they age and dry out.