I used furniture scratch markers on sensor window of the Harbor Freight driveway alarm. At 25 foot the sensor works just fine. I just used the lightest color on the sensor and streaked in on there. The marker does come off with mineral spirits. My original video shows what I camouflaged the driveway alarm with and how I did it. I have mine mounted in a small wooden box I made because the sensor is not waterproof. But for temporary mounting in dry weather this works fine. At a distance its hard to see in daylight plus if you put a piece of tape on the light at night its next to impossible to see.