8mm sensor with 2mm gel hole. The BioMed Electrode is manufactured through a proprietary process using the highest purity chemicals that results in a fine grain homogeneous mixture. The electrodes are then compressed into a 1mm thick sensor and “sintered” (heat treated) for strength and stability. Standard lead wires are PVC insulated multi-strand copper with internal Tinsel for additional strength. The result is a versatile and durable, waterproof assembly that is reusable and resurfacable.