German power metal horde Powerwolf started an auction via ebay in which they sell a huge banner that was used during the Summer Breeze festival 2015. The banner is also signed by Powerwolf.
The band does all this for a good cause since the auction price will go to DKMS which an organisation that fights against leukemia and other diseases of the haematopoietic system. I think, a great action of the band and worth to join.
Find more details via the link.