The Guarder Speeder 2000 Chronograph is an excellent portable chrono unit that can operate in any lighting. Night or day, this chrono will give you accurate FPS/MPS/Joule readings. The Guarder Speeder 2000 has an internal battery that is charged on the included wall charger. There is also a small sleeve to guide the barrel into the tube. The Guarder Speeder 2000 is a high quality chrono from one of the most well known and respected Airsoft companies in the world.