If you would like to keep your F4 windshield in great condition for years to come, follow our simple cleaning instructions (glass cleaner and paper towels) on a regular basis. To keep your rain shedding at it best, use isopropyl (rubbing) alcohol periodically. This removes any build up of invisible debris that may be creating surface tension that will inhibit the movement of rain from your shield. Do this twice, as the first application breaks loose this layer and the second cleaning will virtually remove any remaining debris. Your rain shedding will come back to "as new" performance. As always, call with any questions or comments.