P528 28 in. Plug-End Extension Spring is a Holmes spring replacement for heavier 1-piece / tilt-up / canopy-style garage doors. Two P528 springs - one on each side of the door - can handle a 105 lbs. to 175 lbs. door, with an initial tension of 165 lbs. to 185 lbs. Four P528 springs - two on each of the door - can handle a 200 lbs. - 350 lbs. door. Either 4 c-hook's or 4 w-hook's (sold separately) are required to connect the springs to the jamb hardware.
- 2 x P528 springs support 105 lbs. to 175 lbs. garage doors
- 4 x P528 springs support 200 lbs. to 350 lbs. garage doors
- Length over coils: 28 in.
- Outside diameter: 1-5/8 in
- Wire gauge: 0.207 in. (no. 5 wire)
- Initial tension: 135 lbs. - 145 lbs.
- Maximum allowable stretch: 22 in.