okay i bought a 5 pack just to try them out, and turns out the pump I have takes 12g, which is the exact sise of the co2 canisters at walmart. SWEET!

At that price 3.50 for 5, it doesnt matter if one canister wont fill the whole tire, I can carry multiples...so no biggie..awesome deal...even cheaper if i buy the 15 box. So I'll just make sure I have 3 on me just in case.