You bought the Hephaestus Simulated Recoil Spring Guide & Spring for the GHK AK Series and you have no idea how to install it? Lucky you, Hephaestus Airsoft have just recently uploaded a video on YouTube to give you the proper way of installing it. Once you get to install it properly, enjoy an improved recoil with your GHK AK even if the GBB in its original fault, already has good recoil action.