The cap on the riser containing the Mag Plus probe must be modified to allow the probe's cable to exit the riser. This modification requires making a 1/2"-14 NPT tapped hole in the cap for a cord grip. Two types of drilled and tapped Riser Cap kits are available for purchase, or you may be able to modify the existing riser cap. This Riser Cap kit contains a non-metallic cap which screws onto the 4" NPT riser. The cap comes drilled and tapped with a cord grip.