Ideal Security Garage Door Extension Springs are designed for standard 7' high garage doors. They provide additional lifting power for manual and electric garage doors.REPLACING YOUR SPRINGS If your springs sag or are longer than 25" in the relaxed position, it may be time to replace them. It's important to always change your springs in pairs to maintain proper balance, and to always install safety cables. SPRING SELECTION: CAPACITIES AND COLOURS Garage door springs are colour-coded to indicate weight capacity. Our springs follow industry-standard colour coding. You should replace your springs with the same class of spring you currently have. Verify your current springs before ordering and installing. Some of our competitors use blue on both their 90lb and 140lb springs! If your current springs are blue, ensure that you know your door weight or spring diameter before ordering.