This 1.1" (~30mm) diameter speaker is the perfect addition to any breadboard-based audio project where you need 8 Ohm impedance, and have 0.2W or less of power. The two pins are 15mm / 0.6" apart and fit perfectly in a breadboard or perfboard. This speaker has a durable protective plastic casing that's still lightweight.
Works great with our Wave shield or class D amplifier board (just be careful not to overdrive it)
Adafruit Product Page: https://www.adafruit.com/products/1898