The SC4000 Mastershade® is an is an exterior rolling screen with a larger 5" x 5" cassette box. The SC4000 is ideal for solar control only and for small to large windows, and open porches. The system is available with standard cables. For windy locations, the optional magnetic locks are available for extra stability. With the magnetic locks installed, the screen fabric remains taut when the screen is in its lowered position. If a wind gust lifts the hem bar, the magnetic lock will release the screen fabric from the pressure and then the magnetic lock system will automatically reposition the hem bar back into the lock.* The system is available motorized or manual . and can be rolled up and down as needed. When the shade is retracted the fabric is stored in the built-in closed protective box.