Originally designed to allow a lone technician to test for voltage drop on top battery posts; its handsfree operation is a useful diagnostic tool when a third hand is needed. 
Works with standard 4mm banana plugs 
Probe swivels and adjusts in height to test where you need it
Works great for testing recessed connections 
Clamp tips for added grip 
Available individually as the 21215 (black) and 21216 (red)