Klein Tools VDV501-828 VDV Commander Testing Kit is an advanced voice/data/video cable tester for ensuring smooth installation and troubleshooting of systems, as well as providing PoE testing. Klein Tools VDV501-828 features a full color screen with easy to use interface, internal memory for storage and export of test results, and can simultaneously map and test up to 8 cables, with ID only for 20 cables.