Headroom is the space between the top of the door opening and the ceiling.
Vertical supports (or stiles) span across the width of the door providing stability while the door is being opened.
Nylon rollers are more expensive, and don't last as long, but are much quieter. Steel rollers are less expensive, last longer, but tend to be noisier.
The cycle life of a spring is the mathematical calculation of how many times a spring can be wound/unwound before breaking.
IMPORTANT NOTE REGARDING LOCAL PICKUPS: DDM is considered a life-sustaining company because we are an internet retail company that provides essential products. Due to the recent outbreak of Coronavirus, however, we are changing our local order pickup policy at our West Chicago location. To pick up an order you will need to order first. The quickest way is to order in advance through our online shopping cart. There you can select the local pickup option. Or, you can call 630-293-1337 for assistance, to confirm availability of parts, and to place your order. Once ordered, your parts will be available for pickup in the lobby of our north side front entrance. Longer items will be picked up on the south side loading dock. Please honor the six foot social distancing rule. Thank you for your patience and understanding as we all navigate this challenge together. More information is available on our blog titled DDM Adjusts to the COVID-19 Coronavirus. In the same article you will also find documentation and an answer to the question: "Is a garage door repair company a life sustaining business?"