Intrusive Pig Signallers are mechanically operated and are generally bi directional. They have mechanically operated signal flags which can be reset and are suitable for mounting on both vertical and horizontal pipelines. The indicating device, 'Flag', is normally set in the horizontal position for "pig not passed" and vertical for "pig passed" condition with a manual latch reset to the horizontal position. When moving through production pipework and pipelines so that the time/location of the PIG is known. In addition, it can estimate accumulated debris in front of the PIG which can help you identify in which section of a pipe debris is being built up.