The Radiometer AL100 salt-bridge junction is a double-junction replacement salt bridge for 7.5 or 8 mm diameter reference electrodes. The AL100 has a total length of 70 mm. During measurement, the salt bridge junction (also called the liquid junction protection tube) prevents the reference electrode from being contaminated by the media and vice-versa. The salt-bridge junction consists of a glass tube capped by a ceramic liquid junction.