Note: The SkyWatcher 5kg counterweight for NEQ6 will not be back in stock until December 2021.
Consider upgrading the stock undersized counterweight shaft with the Geoptik NEQ6/EQ6-R shaft, which will allow you to use Geoptik's high quality chrome-plated and machined counterweights.
The SkyWatcher counterweight for NEQ6 fits all mounts with a counterweight rod of 18mm diameter such as: