inputs.text: accurate reliable - used unit 4 occasions first time use 30 minutes sundown although not recommended time day unit worked well another time used cloudy day times worked great last time used sunny day worked great make sure no shadows cast unit followed enclosed recommendations used light diffusers whatever called sunny day not use thehem overcast days near sundownthe chronograph not give unusual unexpected results tested known factory ammo 9 mm 38 special reloaded ammo calibers results expected got widely varying velocities reloads especially ones used flake powder lower recoiling rounds gave lower velocities became good predicting chronograph would read based amount recoil form guni would highly recommend chronograph