A visitor views the electronic sculpture '$' by Tim Noble and Sue Webster at Sotheby's auction house in London June 8, 2015. The piece has a pre-auction estimate value of 100,000 - 150,000 ($152,000 - 228,000) and forms part of a private collection of twenty one works inspired by the US dollar which will be auctioned in London on July 1 and 2. [Photo/Agencies]