The Chinook Optical Tachometer G2 is designed and manufactured in Canada with state of the art microcontroller technology. It's universal design enables it to determine the rotor blade speed in Revolutions Per Minute (RPM) of any R/C helicopter model with an aid of a large viewing window and LCD screen. It uses high quality robust components that guarantees the accuracy and optimization of the head speed in any condition. FEATURES: l Reads a wide range of rotor head speed from 500 to 4200 RPM (2 blade system). (3334/2500 RPM for 3/4 Blade System) for the Elite version. l High accuracy RPM readings within 10 RPM. l Easy to use dial to adjust the RPM speed with onboard memory board to save RPM settings. l Large viewing window for clear visual of model's rotor blades. l Low battery unit indicator l Operates on one single 9V battery (sold separately). SPECIFICATIONS: Height ----- 20.5mm Width ----- 78mm Length ----- 117mm Weight ----- 120 grams