The EL120 electrode has contact posts designed to improve contact through fur or hair. The 12 posts create a 10 mm contact area. The posts are 2mm deep to push through the fur/hair to provide good contact with the skin surface. (As an alternative, use the CAP100C Electrode Cap for increased human subject comfort and reduced application time.) Silver-silver chloride (Ag-AgCl) electrodes provide accurate and clear transmission of surface biopotentials and are useful for recording all surface biopotentials on animals and human EEG. Clean after each use—see "How to Clean Reusable Electrodes." Shipped in packs of 10. It is not necessary to use an EL120 for your ground; you can use a generic electrode for ground. EL120 electrodes requires one LEAD120 per electrode. One CBL201 cable is required to convert Safelead electrode connectors to 2mm pin-style connectors. EL120 Ag-AgCl Electrode, Reusable, with contact posts for hair EL120$15.00 Same Day Shipping - orders with UPS Red or Blue shipping will be shipped the same day if received by 3 p.m. PT (Monday-Friday).