Nokta | SP22 DD 8.5" Skid Plate Coil Cover for Simplex | LMS Metal DetectingNokta SP22 DD 8. 5" Skid Plate Coil Cover for Simplex+ A search coil cover is also known as a skid plate. Detectorists use it to protect the search coil from scuffs and scratches which would occur no matter how careful you tried to be. Stones, pieces of metal, and other objects can easily cause damage to the search coil which is often quite delicate. A coil cover will reduce the potential damage while also making sure it does not interfere with the