KPM Aqua-Boy 218 [218] Pressed bale screw-in Electrode 470 x 25mm. Aqua-Boy Pressed bale screw-in electrode 470 x 25mm used for measuring the internal moisture content of mechanically compressed bales. The electrode comes with a crossbar for screwing it down to the required depth. Only the universal measuring cable is needed for connecting the electrode to the moisture meter.