What are the ropes that baseball players wear around their necks?

Those are Phiten necklaces, which can be purchased at http://www.phitenusa.com/. The company claims that the infused metal in the necklaces provide healthy energy to the wearer. They were developed by Yoshihiro Hirata in Japan, where they are referred to as “Rakuwa.” Internationally, they began to become popular after the 2002 World Cup where many players wore them. Randy Johnson was one of the first MLB to wear them after a trip to Japan.

Monday, February 06 2012
Source: http://explore.phitenusa.com/about/heritage