80% Half Circle Shaped Solar Screens using 5/16" x 3/4" Framing : Half Circle Shaped Solar Screens are measured using two measurements, a width and max height. The max height measurement is taken from the center of the width. 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 half 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 half circle solar screen, say anything larger than 32" in width, for strength we recommend using the 5/16"x1" framing instead of this 5/16" x 3/4" framing.