Low cost chrono from Evike.com... "This is a professional chrono used to measure the firing speed, muzzle velocity, fire joule of bb gun and Airsoft guns. Because it was designed for high power bb guns around 1000 FPS, it does way more and beyond for Airsoft and paintball. This is got to be one of the best Chrono we have available today because it have the widest range of velocity measurement.

As you fire full automatic thru it, it measures the velocity of EACH bb. This is very important because most traditional chrony is not very accurate and it will take you a long time to get 10 reading and take an average. This chrony is very precise, durable, compact and useful. A must have for all real collectors and true airsoft players.

Features:

• Measures 0-3600 shots / minute.
• Measures 2-500 meters/second (7~1800 FPS)
• Measures 0-60 J fire joules of bullets.
• Precision: Testing Error is less than 2%.
• Working Voltage:  External Power DC 9V, Internal reserve battery DC 4.8V (Charger included)
• Size: 105mm x 75mm x 29mm
• Weight: 250g"