UltraStim Snap patented current controlling neurostimulation electrodes distribute current evenly and comfortably through the use of a snap connector rather than a lead wire.The bottom snap is scientifically chosen to match impedance in the entire system to provide even current distribution across the surface, even with a snap.The proprietary silver grid pattern is specially calculated to precisely control electrical current over the electrode surface, while the border around the grid pattern allows for an intentional current roll-off to eliminate edge stinging.Utilizing Axelgaard’s patented multi-layer MultiStick hydrogel eliminates performance problems associated with electrodes featuring single-layer gels.3 models offered:ERP3735-2020: 2 x 2" (5 x 5 cm) Square (4)ERP3735-2040: 2 x 4" (5 x 10 cm) Rectangle, single snap (4)ERP3735-2042: 2 x 4" (5 x 10 cm) Rectangle, double snap (2)