Galaxy has an altitude range of 18,000 feet MSL, marked in 250 foot increments. The face of Galaxy is highlighted with a yellow caution and red warning arc that starts at 3,000 feet. Galaxy contains a durable mechanism made from temperature compensating metals for minimal friction and precision accuracy. There are two basic types of dial face, the standard “glow in the dark” and the traditional white face. The white face does not glow in the dark. The glow face is phosphorescent & provides a background glow to assist in low light conditions. The glow lasts over 2 hours in complete darkness.