The large counterweight, which is 6 - 3/4" in diameter, 2" thick and weighs 18 lbs., slides on the declination axis along with four other such weights.  The smaller weight, which is 4" in diameter, 1 - 3/4" thick and weighs 5 lbs., is attached to the counterweight balancing rods on either end of the telescope tube. The weights are made of cast iron.