The Surebonder Triggerfire staple gun was redesigned to ensure easy, precise stapling with one hand. In Trigger mode, simply squeeze the handle to pre-set the staple gun, position the tool on the work surface, and then squeeze the Trigger to set the staple. In normal mode, the functions as a traditional staple gun. The heavy-duty construction and easy-to-use design make even the toughest projects a breeze. Trigger mode - switch the knob to trigger mode, squeeze the handle to pre-set the staple gun, position the staple gun on the work surface, and squeeze the trigger to set the staple. Normal mode - switch the knob to normal mode, place the staple gun on the work surface, and squeeze the handle to set the staple. (just like a traditional staple gun). Adjustable staple depth - (+) mode is for more power when driving staples into hard surfaces. (-) mode is for less power when driving staples into softer surfaces or in applications where the staple does not need to be driven flush.