Sugidama (杉玉) [lit. cedar ball] is a big sphere made out of japanese cedar, which is usually hang from the eaves of the entrance of a sake brewery. The brewers order and put it up, in order to show that freshly-brewed sake is available for sale. As time passes, the ball’s color changes from green to yellow, thus customers know that the sake is not fresh any more.
Nowadays, anyone can buy a sugidama online (from rakuten ) for as little as 350 euros.