I pretty sure i saw one on ebay yesterday 1/2" to 1/4" (6.35mm),http://www.ebay.com.au/itm/Lovejoy-coupling-1-4-X-1-2-spider-3-piece-set-/330619477639?pt=LH_DefaultDomain_0&hash=item4cfa74de87, so i would presume that you would be able to buy a step down coupling. I am going to try these guys on...