A must have for all rocketeers! And a great price too. This is a sophisticated and lightweight electronic payload for accurately measuring your model rocket altitudes. The Estes Altimeter has a 4 digit LCD read out and displays in English or metric units. Accurately measures model rocket launch altitudes from 0 - 3000 m (0 - 9999 feet) and can store up to 10 consecutive flights! A replaceable alkaline battery is included.