P728 28 In. Plug-End Extension Spring (0.177 In. No. 7 Wire)
P728 28 in. Two P728 springs – one on each side of the door – can handle a 90 lbs. to 150 lbs. door, with an initial tension of 110 lbs. to 120 lbs. Four P728 springs – two on each of the door – can handle a 150 lbs.