8 foot Green Lead with 27-C (40 Amp Clip and Brass Thumbscrew

The brass thumbscrew allows this test lead to be screwed into the bottom of either a Model IA Voltmeter or a Model DPM Voltmeter, replacing the electrode in both cases. Such a substitution allows these voltmeters to take 'structure-to-structure' potential difference readings (as opposed to 'structure-to-soil' potential difference readings).