[tobymoryr]

why would it be necessary to purchase one?

 

[resurrection]

yay i know this one... its air source adapter. its where you screw in your CO2 or HPA tank. Upgrading it would increase efficiency , and you can also have one with an on off valve to control air flow into the marker

 

[the_real_kaz]

Your marker probbly already has an ASA so don't worry about it.