With the Pro Chrono you get the features and quality of a high dollar chronograph at an affordable price. Features a velocity range of 22-7000 feet per second, temperature range of 33-100º F. Size: 16x4x3-1/4". Power requirements: one 9 volt alkaline battery (not included). Guide wire size: 3/16x16". Mounting hole thread: 1/4"x 20".