Internal Electrodes are made to order to fit the exact Inside Diameter of your pipe. Internal Electrodes are made for use with High Voltage (Silicone-Rubber material) and Low Voltage (Sponge material) Holiday Detectors. The electrodes fit pipe ID starting at 2” and continuing up to 36” and beyond. Internal leg supports can be added to center and support the electrode to ensure intimate contact between the electrode and the coating. Custom sizes and materials also available.