The piezo is a PIEZO DIAPHRAGM  - NOT a BUZZER.  The red and green LEDs are clear-type and high brightness.
The button changes the Probe into tone-producing. Each press of the button produces a different tone.
The 10mH choke allows the piezo diaphragm to produce a loud output with 5v supply.

The clips come with the kit.
They are small and easily clip on to a resistor lead.