Rods are available in the following styles: 3/8" Round, 3/8" Hex, 7/16" Hex, and 1/2" Round. All the rods are made from a high strength alloy steel. Using the 3/8" Round rod as a basis for comparison, the 3/8" Hex rod is about 20% stiffer than the 3/8" Round rod. The 7/16" Hex rod is approximately twice as stiff as the 3/8" Round rod. The 1/2" Round rod is approximately 3 times as stiff as the 3/8" Round rod.

As the size of the rod and tip increases (from 3/8" to 7/16"), additional effort will be required to push the tool into the ground.

The following table describes which probes and which rods will work with each other.