Penis enlargement using weights falls under the same category as penis extenders in that gains are achieved by traction. Weights are hung from the penis by a hook and a contraption (usually innertube rubber with a hose clamp) that holds on snug to the end of the penis. This method of penis enlargement is usually for veterans of penis enlargement that understand the risks involved with hanging weights. In addition, most veterans also make their own hanging system since the piece that hangs on at the end of the penis must fit snug. As we all know each penis is not created equal, so the best weight hanging system is usually one that you build yourself.
Penis enlargement using weights is particularly dangerous due to the fact that a heavy weight is attached to your penis very snuggly. Should some horrible accident occur like you falling over, do you really want some long hanging device connected to your penis? Remember, this must fit snuggly around your penis since a weight is constantly pulling down, so you know it's not going to release easily. Don't say we didn't warn you!
Although there is a very small handful of companies that sell weight hanging systems, it is best to build your own to achieve a proper fit. There are many documents online detailing how to build your own device that will fit you best.