Amazon.com: Gikfun 2" 4Ohm 3W Full Range Audio Speaker Stereo Woofer Loudspeaker for Arduino (Pack of 2pcs) EK1725 : Electronics
Amazon.com: MakerHawk 2PCS 4 Ohm 3 Watt Speaker for A rduino Single Cavity Mini Speaker Full-Range Cavity Mobile Portable Advertising Machine Speaker with 11mm Line Length JST-PH2.0mm-2 pin Terminal : Electronics