In design, we specify custom wax formulations that will expand when heated, activate a snap action electrical contact and transfer the electrical signal to the fan controller In production, all thermal switches are factory-calibrated to make electrical contact at the specified lower-temperature set point The switch is designed using a formed bimetallic contact arm. The bimetal contact movement is achieved using the different expansion rates of two metals fused together. This is a creep action device, provides precise performance Robust design and high grade materials meet the stringent demands of today's service professional In manufacturing, we custom form the wax pellets for different temperature range specifications. All units are calibrated and tested to confirm switch actuation at their specified temperature As a global manufacturer of original equipment ignition products, we maintain complete quality control throughout the manufacturing process from componentry to finished productPackage Dimensions: 2.0 x 1.5 x 3.5 inches Package Weight: 0.155 lb Package Quantity: 1 UPC: 091769080136 Attachment Method: Bolt On Connector Gender: Male Connector Quantity: 1 Connector Shape: Round Connector Type: Plug In Terminal Gender: Male Terminal Quantity: 1 Terminal Type: Bullet Thread Size: 3/8-18 " Country of Origin: MX