surrree but do u really want your gun decided on the size of a tank? u can always sell the 12 oz tank and take the three dollars, buy a 20 oz tank which will be cheaper, soooo. the tlx pack with sold 12 oz and bought 20 oz is cheaper than xtra pack, but with better gun! what a great deal!!
look for the 12 and the 20 oz, they are 2 dollars diff, both Pure Energy
http://www.xpaintball.com/co2bottles.html