80% Quarter Circle Shaped Solar Screens using 5/16" x 3/4" Framing : Quarter Circle Shaped Solar Screens are measured using three measurements, a width a height and a center height. The center height measurement is taken from the corner to the center of the arch. This solar screen is made out of the 80% fabric, we recommend the 80% fabric for all windows that get 4 hours or less of sun. We recommend the 90% fabric for windows that get 4 hours or more of sun, generally those windows that face the West. This screen is made out of the 5/16" x 3/4" wide framing. We do not recommend building large quarter circle shaped solar screens out of this framing. This size of framing is good for smaller sized screens. If you are needing a larger sized quarter circle solar screen, say anything wider than 30", for strength we recommend using the 5/16"x1" framing instead of this 5/16" x 3/4" framing.