Essential tool for seasonal inspections: This circulation pump rotation tester is very useful at the beg. Versatile: In addition to testing the circulation pump, the device can also check the operation of the oi. Clear indication system: The built-in indicator can effectively display the magnetic field and rotation. Compact and portable: This tester is small and portable and can be hung on a keychain. Simple four-step operation - only for sets with valve openers:1. Turn off the power first and remove the motor coil. 2. Put the tool on the valve stem and make a "click" sound.3. Without a "click" sound, rotate the magnet in the opposite direction. 4. After completing the manual operation, remove the solenoid valve magnet, rotate the motor coil, rep. Color: As Shown Material: plastic Package Contents: 1*coil tester Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.