Hello,

Thanks for your interest in our canopy. There is an aluminum monorail track running down the middle of the pergola, attached to the underside of the rafters. This track is running perpendicular to the rafters, and parallel to the beams that the rafters are resting upon. The canopy fabric is connected to and supported by aluminum "wings" that hang perpendicular to the aluminum track, and extend to within 1/2" +/- of the inside faces of the inner-most beams. These "wings" can slide down the length of the track, and occur every 24"-30" +/-. The front-most wing (the one closest to you in the photo) has a large eye-bolt hanging down, and you hook a pole (provided with canopy) into this eye-bolt and pull the canopy along the track to cover your seating area....or push the eye-bolt to the back of the pergola to retract the canopy. Attached are 2 close-up photos of the canopy in this picture, which allows you to see the track a little more clearly. I have also attached 2 photos of an arched pergola, with canopy fully retracted and fully opened. The mechanism for the arched pergola is the same as for the flat-top pergola. The only difference is that the "wings" for the flat -top pergola are straight, and those for the arched-top pergola are bent to the curvature of the arched pergola rafters.