Features: 100% brand new and high quality Insert tester directly into power base, do not insert adapter. Before inserting your circuit tester into the power supply base, make sure the corresponding circuit breaker is in the OFF position. After the circuit tester is inserted into the power socket, switch the corresponding circuit breaker to the on position. If the power base connection is correct, notify the user that the RV can be safely inserted. Because the wiring condition is unchanged, the tester can be removed from the power base after use. If the power socket is incorrectly connected, contact the responsible person or professional maintenance personnel. And be sure to test the power base again before use. The tester has no surge protection function, please use it in a dry place. Package Includes: 1x Circuit Analyzer Specifications: Material:Plastic,Copper Type:30A,50A 30A Net Weight:105g 50A Net Weight:142g Plug/Receptacle Type: 14-50P Function: To verify if the power source is correctly wired. note: Please allow 1mm errors due to manual measurement. Due to the difference between different monitors, the picture may not reflect the actual color of the item.