Although professional wrestling is worked, there is a high chance of injury, and even death. Strikes are often stiff, especially in Japan and in independent wrestling promotions such as Combat Zone Wrestling (CZW) and Ring of Honor (ROH). The ring is often made out of 2 by 8 timber planks. Many of the injuries that occur in pro wrestling are shoulders, knee, back, neck, and rib injuries. Chronic traumatic encephalopathy and traumatic brain injuries have also been linked to pro wrestling, including in the double-murder suicide case involving Chris Benoit. Professional wrestler Davey Richards said in 2015, "We train to take damage, we know we are going to take damage and we accept that".