have a solid bare-metal to bare metal contact to the frame of the car. if you have have problems with this antenna, check out the ground before you do any thing else. i would not put this antenna on a mag mount. if it ever got loose from wind it could be a big problem. getting a good ground could be a problem too.
the antenna only comes with 3 taps. it takes two taps to cover 40 meters so that, you can only have one additional frequency. i ordered additional taps and i can do 6, 10, 12, 15, 20 and 40 meters. it is much more convenient to move 