Although most of these bulbs will have a visibility range of 1 to 2 miles, actual target illumination depends on many factors such as weather conditions, size and color of target, background, the color of the light source, characteristics of the reflector, supplied voltage, etc.
Specifications and ranges provided are approximate and are offered only as a guide to compare bulbs
Candlepower (or Candela) is a measure of light radiance at the source, and is provided for comparison purposes; how much of that light gets to your target will vary
Lumens are a measure of illuminance of a target at a distance; a lumen is equivalent to 1foot-candle of light per square foot of target; again, the values given in the table are relative