1" Dia x 1/4" Thick NdFeB Disc Magnet, highest grade available, Ni Plated with Matte finish, Axially Magnetized (the top & bottom flat faces are the north & south poles). The disk has a 0.365" x 0.195" 90 degree taper hole. Use with #8 or #10 flathead screws. (disk is tapered on both sides). Maximum pull: 26 pounds.