6mm? disk. The Strom is 5 and the Guzz is 4.5. Picked up a couple of planks from the recently demolished Penguin island ferry jetty. Will pass them on to a mate who most likely use them in a table 100yr old cast iron balustrade panels. Seems the way forward may involve selling bits and pieces. Old mate offered me $200 for this I countered with 250. Will see.