Mag-Probe, Model "Hs"
Part No. 12-201
Bartol's Mag-Probe is a non-contact instrument that tests AC or DC relay and solenoid operation. The Mag-Probe is sensitive enough to detect the magnetic field generated by tiny "ice cube" relays, and is available in standard and high-sensitivity models.
For information on how much revenue you could be losing by not using the Mag-Probe, see the manufacturer's video and spreadsheet below: