This large crystal earplug is best used for a crystal radio. The delicate solder joint may give out if used with a regular radio. It comes with an 1/8 inch stereo plug. If wired directly into a crystal radio kit use the tip as one conductor and the shaft base as the other conductor. It is built for a high impedance circuit with low power as found in a crystal set.
If you want a smaller, standard earplug try our small crystal earphone.
Stereo tip plug. 6-foot cord.