Introducing the Tractor Trailer Round Pin Circuit Tester, an essential diagnostic tool for big rig truck owners and mechanics. This tester is perfect for testing the electrical circuits in your 7-way round pin trailer connectors. Designed by IPA, this tester is reliable and efficient and comes with a manufacturer part number of 7865L. With its easy-to-use interface, you can diagnose any electrical faults in your trailer within minutes. So if you want to keep your big rig truck running smoothly, get the Tractor Trailer Round Pin Circuit Tester today. These are brand new. Packaging may have a few blemishes. XX2