A LAN cable tester is an instrument used to examine copper or fiber network cabling. Depending on the tester, it may perform continuity testing, cable qualification, certification, bandwidth verification, wire mapping, PoE testing, network diagnostics, fiber testing and professional test reporting.
Professional cable testers are designed for commercial and industrial environments. Many are expensive when purchased new and can remain useful for years when properly maintained.
Second hand value can depend on the brand, model, generation, supported cable categories, maximum test frequency, certification capability, network speed testing, fiber capability, PoE capability, battery condition, screen condition, calibration history and included accessories.