I needed this extra weight to balance my rig. Normally I use the (high quality) Sky guider pro mount for camera work, using a Canon 60D and a telephoto lens, but now have a Stellarvue ST70t. To balance this slightly heavier rig you can go one of two ways, eg, increase the length of the balance arm, or secondly add another weight, keeping both very close to the pivot point.
In choosing the second option one can keep the Moment of Inertia (MOI) very low, which reduces the stress on the mount, and still have a nicely balanced kit.
This counterweight is of very good quality and matches the kit weight perfectly. Simple addition to my rig, works great. Very happy with my iOptron mount. The service by Ontario Telescope was very good as always, shipping was quick.
Reviewed by: (Verified Buyer) Ian Dixon from Winnipeg, Canada on 3/28/2020