Here is a video of a Cookson 18' x 20' Service Door. This video was shot upclose to capture how smooth the door operates when perfectly aligned. The video was shot via phone.
Cookson 18' x 20' Motor Operated Service Door
Notice how quiet and smooth this door operates.
Cookson 10' x 9' Motor operated Fire Door
Notice that the door stops perfectly at the header and immediately at the floor, providing a nice seal.