A frequency circuit (sold separately) multiplies the RPM signal to allow it to be read by most fan tachometer headers (such as those found on ATX motherboards). This signal is intended to allow fan detection software (including BIOS) to enable the appropriate alarm or shutdown procedure if the flow meter impeller stops rotating. The "RPMs" represent approximate flow meter coolant in mL/min, and not revolutions.
Wire length is about 28" (70cm). Primary materials are nickel-plated brass and acrylic with an external aluminum shell.