Oct 24, 2022 · Happybuy 5KW Diesel Air Heater 12V Diesel Parking Heater 5000W Diesel Heater with Digital Switch for RV Bus Car Motorhome Boats 【ADJUST TO IDEAL SIZE】Roller quantity: 2; Roller diameter: 6″x1.5″; Roller adjustable range: 0-0.065″. Adjustable roller allows you to change crush settings with the turn of a knob.