Tester for temperature sensors for nautical refrigeration systems, it has two RJ-11 ports for comparing sensors, easy operation, just move the selector to positions A, B or C to select the group of sensors you want to test. Features rechargeable Lithium battery USB-C charging port, Fast charging in 20 minutes (using 2A charger) What's Included in the Box: USB-A to USB-C Charging Cable 2x RJ-11 adapters for 2-wire sensors operation manual.