Hi all found this in a Repco Catalogue in Victoria hope it helps someone who need to buy one (I ope the link works if not look up Repco go to Catalogues  on page 4) Cheers Jojja

 http://catalogues.repco.com.au/catalogue/price-down/5fkvxj8vn.html?pid=promotedCatalogue&retailerName=Repco#pageNo=4&offerId=15326659234916

I bought the Hayman Reese one a couple of years ago. Quite accurate within 2kgs vs a weighbridge

We've had ours for 6 years, they are a good guide. Ball weight is always around what was registered on our local weighbridge.

If your not ''living on the edge'' weight wise you've got no worries.