All window treatments should be made slightly smaller than the window opening to prevent rubbing against the window frame when the blackout shade is raised or lowered, allowing some light to shine through. Additionally, we understand that there can be gaps between the brackets and the wall, and even the bottom of the curtain might not completely block sunlight. Light Blockers are L-shaped plastic pieces placed in front of or behind your window covering to block the uncovered portion of the window, effectively minimizing light leakage and ensuring maximum light control.