BB2K Airsoft's Bruce does a more comprehensive video review on the Acetech AC6000 Chrono... "Today I introduce to you the Acetech AC6000 Chrono, which has everything on board to measure the energy (Joule, FPS, m / s), the Rate of Fire ROF (RPM, RPS). The MAX, MIN and AVG values for FPS and ROF are displayed and the last 25 shots are saved. Up to 5 BB types can be stored, which you use more often. So caliber 4.5mm, 6mm, 8mm, 17.3mm (.68 Rubberballs) pose no problem. Of course, also the appropriate weight can be set and stored. Thanks to 36mm tube / aperture, the chrono is not for the sniper mission :-)"