The A19D Series Surface Mounted Temperature Controls (Figure 1) Are Reliable, Durable On/Off Temperature Controls With Line-Voltage Single Pole, Double Throw (Spdt) Switches. The A19D Series Controls Are Designed Primarily For Fluid Piping Applications And Include Two Adjustable Mounting Straps For Mounting The Control Directly To A Pipe. The Sensing Element Has A Liquid Charge And Provides Fast Response To A Change In Temperature. A Range Adjustment Knob And A Visible Temperature Scale Are Standard. Models Are Also Available With A Snap-In Plug In The Cover For Concealed Screwdriver Slot Adjustment. Made in United States. Manufactured by Johnson Controls.