Steel mounting discs are compatible with the MobNetic Pro 90 & Mob Mount Magnetic phone mounts. Securely mount any magnetic phone mount to a non-ferrous surface in boats, cars, trucks, office & workshop. Mob Armor Mounting Discs are .38mm thick/1.5” diameter & designed to secure any brand/type of magnetic phone mount. Universal smartphone compatibility: iPhone & Android- Samsung, Google, Motorola, LG, HTC, Blackberry. Single placement mounting discs use powerful 3M VHB non-marking adhesive to secure magnetic mounts.