Red and green are great in daylight and overcast outdoor light, but the yellow dot really optimizes those early morning or later afternoon hours when the sun is going down. Powered by one easy to find CR2032 battery, the RGY has a run time of 100 hours. Windage and Elevation are adjustable in 1/2 MOA clicks and the RGY is shock rated for 800G. The RGY comes ready to mount on either a Weaver or Picatinny rail.