DEF Digital UL Meter， Engineered Polymer In Line Turbine Meter That May Be Installed At The End Of A Hose Or Plumbed In A Fixed Pipe Installation With The 1" NPT Inlet/Outlet， Use For DEF， Agriculture Chemicals， Non-Potable Water， & Many Other Chemical Applications， 20 Pre-Set Calibration Factors Based On Fluid Type Or Can Be Easily Calibrated In The Field， Uses 2 "AA" Batteries That Can Be Easily Changed When Needed， A Low Battery Level Alert Will Notify The User When It Is Time To Change The Batteries.