Panel is an electrical switch panel and jacks are hardware devices, which work like plug points. These panel jacks are calibrated and color coded for easy identification, as per ANSI standards. There are jack panel boxes which accommodate multiple circuits. These jacks have two or three prongs depending upon the type and brand. RTD and thermocouple panel jacks are usually round and standard size with three prongs. Therm-x is a well-known manufacturer of standard panel jacks, and we make it in various configurations. Most of our standard jacks fit all the miniature and standard sized TC connectors.