This model is a standard “Large” model Van De Graaff. The 250mm diameter ball is in proportion with all the rest of the instrument’s construction.
This model now uses an insulation tube to protect the belt, but the pulleys, the belt and the combs are accessible for inspection, cleaning or adjustment at both the top and bottom ends of the tube. The belt is a long lasting Silicone rubber and both performance and reliability is excellent.
The whole instrument can easily be dismantled down to the components to reduce size for transport.