The screen should be a white projection screen (1.1 gain max) (No silver screen) or a flat, non-glossy, white wall. It is best to use a screen with a light-blocking backer material to help from losing light through the back. It is also best to use a traditional vinyl material type screen. Cloth screen material tends to absorb light or allow too much to pass through. The screen should be a 16:9 aspect ratio. If a non 16:9 screen is used the image will just not fill the screen, but will still work. The system is designed to be used on an 8 ft to 12 ft widescreen. A flat wall with no texture painted flat white with no shine to the paint can also be used. It is also important that the screen surface is flat with no waves in the surface for an even image.
As an example, we use the Elite Screens Yard Master 2 in 110" for trade shows. (Note: these have a gain of 1.3 but work fine with our system.)
https://www.amazon.com/gp/product/B00V8TGR8G/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1
If you want to go with a bigger screen we recommend going with the Yard Master Plus Series which allows the screen to be mounted closer to the floor.
https://www.amazon.com/gp/product/B07894W8Q1/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1