For those heavy doors and gates where you need a large weldable spring there's this 12"" spring. It comes in black with heavy duty adjustable screws. Receive a quantity discount at three levels, 50+, 100+ and 160+.
Heavy Duty Pneumatic Door Closer. For Metal or Wooden Doors, For Outswinging Doors, Adjustable Closing Speed, Internal Spring to Prevent Rod Bending, Black Finish.
9" Weldable Spring Closer. For Gates or Doors, Black with Hevy Duty Adjustable Screws.