This is a graph showing the 50% increas in shots that one get per fill using the HDD!!!
Also, since you are wasting less air (that normally would make more noise) it is MUCH QUIETER.
Here is a graph of a stock vs modified .25 cal Marauder. Note the number of shots of a stock Marauder (Lower in black), vs one with the HDD installed (Upper, in red). That's a 50% increase in usable shots (from 22 to 33)
Only $99 installed!!!!