As he was aware that his device required a bigger band than a telegraph, he found some means to avoid the so-called "skin effect" through superficial treatment of the conductor or by acting on the material (copper instead of iron). He successfully used an insulated copper plait, thus anticipating the litz wire used by Nikola Tesla in RF coils. In 1864 Meucci later claimed that he realized his "best device", using an iron diaphragm with optimized thickness and tightly clamped along its rim.