they are mounted under the guitars saddle,
they yield consistent sound and are practically invisible.they look like a long string.
and the saddle in the white thing on the bridge of the guitar.
magenetic pickups(sound hole pickups)
they look like a metal piece or may look like a long plastic bar with 6 holes.
under each string, they are situated in the soundhole, and are visible clearly.
they are attached to the guitars top, they look like coins and are glued
on the underside of the guitar