The Tool Aid Clamp Probe Set, No. 21200, was originally designed to allow a lone technician to test for voltage drop on top battery posts, but its handsfree operation is a useful diagnostic tool when a third hand is needed. The probe, under spring tension, adjusts in height within the housing and rotates 360 degrees so users can test where they need to. The probes accept a standard 4mm banana plug, allowing technicians to use their existing equipment. The Clamp Probes are also available individually as the 21215 (black) and 21216 (red).