Direct Replacement To The A419Abc-1C The A421 Series Electronic Temperature Controls Are Single-Stage Controls With A Single-Pole, Double-Throw (Spdt) Output Relay. A421 Controls Feature A Bright Backlit Lcd With Adjustable Brightness And A Three-Button Touchpad Interface That Can Be Set Up To Restrict User Adjustments. An Led Indicates The Output Relay's On/Off Status. Standard A421 Series Control Modules Have Simple On And Off Temperature Settings For Heating Or Cooling, An Adjustable Anti-Short Cycle Delay, Temperature Setback, And Sensor Offset Capability. Made in United States. Manufactured by Johnson Controls.