The Tippmann A5 Classic double trigger kit is a drop-in kit that replaces the single trigger and trigger guard. The kit includes a double trigger and a tournament legal trigger guard. To install the double trigger simply remove all gas sources and disassemble the marker to the point of removing the left half of the markers receiver. Remove the single trigger and guard. Then replace with the double trigger and guard. Now replace the receiver half. It's that simple!!!!!!!