The Rod Counter is made from welded steel and aluminum and is designed to count the fiberglass rod as it's spooled off the Duct Rodder frame. It fits all our Standard and Detectable rodder frames and works with all our diameter rods, from the small and compact 3/16" diameter Reel Rod to the heavy duty 1/2" diameter Ruf Rod. Smaller rods require the S-bar Frame Adapter. They are available in both imperial of metric measurement versions.