The standard method of mounting toroidal transformers to a chassis is with a dished steel washer, with the transformer interposed between cushioning gaskets, with this hardware held in place by a single bolt passed through the central hole of the toroid. These mounting kits are supplied with standard transformers. For other mounting options, please see the custom transformers.
Caution: The metal chassis should not touch both ends of the mounting bolt. This causes a shorted turn, which would overheat the transformer rapidly and cause its destruction.