Decrease quantity for MSR PolyGard MA-4-2077-A-F Solid-state semi-conductor leak detection Sensor (4-20 mA / 2-10 VDC) for Freon / Refrigerant (R134A, R22, R401A, R407C, R123 etc)0-2000 PPM, 24VDC, 3 wire, economy version. Quantity Increase quantity for MSR PolyGard MA-4-2077-A-F Solid-state semi-conductor leak detection Sensor (4-20 mA / 2-10 VDC) for Freon / Refrigerant (R134A, R22, R401A, R407C, R123 etc)0-2000 PPM, 24VDC, 3 wire, economy version. Add to cart