Fitting & Installation Instructions PD Extinguishers recommend that you always retain a copy of the fitting instructions for reference at all times. 4.25L AFFF Mechanical System Fitting Instructions4.25L AFFF Electronic System Fitting Insructions4KG Haylo Mechanical System Fitting Instructions4KG Haylo Electronic System Fitting InstructionsElectronic Systems Wiring DiagramElectronic Systems Wiring Instructions