#3 The yellow tubing on the fence is yellow drainage type tubing. It is made for baseball field fences and it isn't cheap. It is cut down the entire length of the tube so that it can be put over the top of the fence (usually with a tool). It is there to warn the outfielders that they are close to the fence and to protect them when they try to catch a ball over the fence.
+2 1. vhedges commented 11 years ago on video Brutal Self Inflicted Nutshot