BioStim Rectangular Adhesive Pigtail Electrodes, 2 x 4 (5 x 10 cm), 4-Pack.BioStim Pigtailed Latex-Free Electrodes are Cloth, Carbon Layered, Pre-Gelled, Reusable electrodes. These electrodes are made with the highest clinical standards. Pre-gelled electrodes can provide repeat applications for up to two weeks or more.