The Virgis Filter clogging indicators indicate clogging of the filter and therefore allow correct maintenance to be performed, in order to protect and optimize the operation of the filter itself. They are resistant to vibration, breakage, weathering, corrosion, dust and dirt to ensure reliable readings of the filter restriction. Different colored labels uniquely and quickly identify the calibration value of each indicator. Different threads and different versions are available: (version with standard connector, protection class IP 44); (version with connector amp protection class IP 67).