This Counterweight set includes a 14mm counterweight shaft and 2 - 2.5 lb counter weights along with all the necessary hardware to attach it directly to the primary mirror box. There is a rubber cover over the receiving hole on the mirror box. Remove the cover and screw the shaft into the hole. Add the counter weights required to get your telescope perfectly balanced even if you are using heavy eyepieces with coma corrector, a binoviewer or large finder scope. Counter Weight Set fits all three of our Explore Scientific Dobson Telescopes.