Differnce between an on off and just asa?

[darwin]

I am pertty ignorant on the air thing as i still dont actually own one i am borrwing a preset from a friend

[Branchvillian]

Just an ASA would be like having your air on all the time that it is screwed into the asa. With on on/off, you can have your tank screwe in, but with the twist of a knob, it's off!

[Methylphenidate]

ya what he said