Cleaning windows without streaks is easy. Always use streak free window cleaner, such as Ammonia Fortified Glass Cleaner or Non-Ammoniated Glass Cleaner, and two CLEAN towels (note: Ammonia fortified Glass Cleaner is not recommended for use on After-Market Window Tinting as it can turn the tinting purple) . Use the first towel for initial wiping and the other towel to polish or dry the glass. The second towel removes the streaks, and it should never be wet. TIP: Clean the interior windows horizontally and the exterior windows vertically. By doing so, you can easily identify which side of the window the streak is on!