Airsoftjunkiez show you how to install the HPA trigger from SPEED Airsoft which they have them in stock... "The new SPEED HPA triggers will incorporate dual adjustment set screws which will enable a trigger pull under 1mm with ease. The new SPEED HPA triggers will also include a specially designed coil compression spring that reduces the pull tension, so players with the Polarstar and Wolverine systems can rip off lightning fast strings easily even in semi-automatic mode."