A “Shim” refers to a small, thin piece of ferromagnetic material, often steel, embedded into or attached to a coin or gimmick to make it magnetic or interact with magnets. This modification allows the coin to be used in conjunction with magnetic devices, such as holdouts, vanishing tools, or magnetic shells, enabling a wide range of effects like vanishes, productions, and transformations. Shims are commonly used in gimmicked coins like “Shim Shells,” where the shim is integrated into a hollowed-out coin to enhance its versatility. These coins can adhere to magnets or magnetic surfaces, making them essential for routines requiring precise control or concealment of the coin. The use of shims exemplifies the ingenuity of coin magic, where subtle modifications create seamless and astonishing illusions.