The Zoll Liquid Gel ECG Monitoring Electrodes (600 per Case) offer stable and reliable ECG traces with low signal noise. Each electrode has adhesive with excellent adherence that withstands difficult conditions found in emergency situations. They are made of medical grade white polyethylene, and feature high-tack medical grade adhesive ideal for all skin types.Warranty: Until Use or Expiration (24 Month Shelf Life).Zoll ECG Monitoring Electrodes are designed for use in emergency, surgery, ICU/CCU, stress test, and EMS applications / environments with the E Series, M Series, R Series, or X Series defibrillators.