This laser is useful for both daytime or nighttime rangefinding and illumination. Right out of the box as shipped, I had it easily and quickly mounted on my AR platform in moments with the rail mount provided, and the click pad adjusted to rest at the edge of the trigger guard. I Highly Recomend this product, & NOT recommend using this around airports, as it could easily blind a pilot and cause an accident. Even on a sunny day, this will put a brightly colored spot directly on your target from a hundred yards away. At nighttime, you’re not likely to have enough open ground for the laser to dissipate on you. This makes all other laser lights look like wimps in comparison, and is no larger or heavier than the much weaker competitors! At about the same or even lower price, too!