This is a slider slingshot front door fork that you need to use with a metal square tube. You need to choose a metal square tube with a size suitable for the front door, and machine a hole at the appropriate position at the front end of the metal tube to trigger the mechanism to fix the front door to the front end of the metal tube during sliding. This metal slingshot front door requires a slingshot rubber band set consisting of 10 rubber bands. The rubber band group is a consumable item, which can prevent scratches and avoid light to extend its service life. The package contains screws to secure the slingshot gun trigger mechanism. Each component must be firmly fixed to prevent breakage and injury.