You can refill the tanks with threads on the end, you can not refill the disposable 12 grams cartridges.
If you are talking about the 12 gram CO2 cartridges, then the answer is no. They are a one time use disposable item.
No. Most airsoft guns that run off of CO2 use unthreaded, disposable 12 gram cartridges.
If you are asking about the small 12 gram C02 cartridges, then,"No" they are not reusable. However, larger tanks (like 20 oz) with pin valves on the top are refillable.
Any CO2 tank with standard threading. It cannot use un-threaded disposable 12 gram cartridges without an adapter.
No, they must be filled (and not with air). The only exception is the silver 12 gram cartridges for pistols and stock class guns.
No. the only full air canisters are 12 gram CO2 cartridges, all others are sold empty under law.
A 12 gram canister is made up of aluminium. This makes the canister light and easy to dispose of. You cannot refil 12 gram CO2 canisters.
they are all the same
You need to buy what's called a 12 gram changer. Or if your maker has an open port for the 12 gram cartridge, you can buy what is called a "dummy" 12 gram, which fits into the port, but allows a remote to be attached, which can be attached to a regular CO2 tank.