Tears of the Kingdom
"A Zonai device that shoots a shocking bolt from its horn when struck. Oddly, only the horn conducts the bolt. The rest of the head is safe to hold."
Otherwise, they can be found in Zonai Capsules from Device Dispensers or Treasure Chests; or lying around in the overworld. If removed from a capsule, they cannot be returned to it, although they can be fused to weapons or shields.