Holmes P728 one piece garage door spring.

Note these are usually best replaced in pairs.

There are normally 2 SL728C springs on a heavier 2 car 16-foot or larger aluminum one piece garage doors one on each side.

There are normally 4 SL728C springs on a heavier 2 car 16-foot or larger wood one piece garage doors one on each side.

Holmes SL728C springs will have an orange sticker and SL728C stamped on end of the spring.

These are also popular replacement Toyhauler Door Springs, check your Manufacturer for proper spring mdl. #