"spits out 22 titanium staples at a trigger pull"

Here again, with Reader's Digest reading this morning, among the line making me longtime lingering to figure out its context, triggers me to ask for help by sending another email. It is about gastroenterological operation, stomach cutting helping obese people lose weight. The line I have difficulty in understanding is as follows:

"The EEA device spits out 22 titanium staples at a trigger pull, accomplishing in a split second what once took long minutes of painstaking needlework."

ANSWER: "Spits out" means to eject or put out and "at a trigger pull" means the small lever one presses with the forefinger. Thus, the device is referred to as a staple gun and you operate it by pulling on the small lever which releases the staples automatically; much in the same way when you pull the trigger to shoot a gun and the firing mechanism is activated and thus fires the bullets. Have a nice day. "Ambiguous Bill"