5kg counterweight for iOptron mounts. This CW is designed for following iOptron Mount: CEM70/CEM70EC/CEM70G, CEM60/CEM60EC, GEM45/GEM45EC/GEM45G, CEM40/CEM40EC/CEM40G* (for late version with 28mm CW shaft), iEQ45 Pro iEQ45. It can be used for other mounts with a 28mm diameter counterweight shaft. *Check your CEM40 mount CW shaft diameter before ordering.