isual clogging indicator (pressure gauge) for hydraulic filters. Operation: Monitor differential pressure or back pressure., Chromatic Scale: The dial is divided into colored sectors (usually green/yellow/red) for an immediate reading of the cartridge status., Calibration: Usually set to signal clogging to , the standard value for filters on the return line.1.2 bar (17 psi), Thread: Radial attachment (from below) from .1/8" NPT, Application: Mainly used with Parker series filters 12AT50AT (return line).