Our High Quality Mooring Pendant 100% Nylon rope has three characteristics that make it ideal for dock line and mooring line. 100% Nylon rope is incredibly strong, it is very stretchy, and it resists the harmful effects of sunlight better than any of those expensive fancy-name synthetics. 100% Nylon ropes value of strength is self-evident, but the benefits of elasticity may not be as obvious. When your boat surges against an unyielding dock line / mooring line, the load on the line goes from zero to the maximum at the instant the line comes taut. The likely consequence is a broken line-not unlike how you might snap a piece of thread with a jerk. Even if the rope is strong enough not to break, it is hammering cleats and bitts with every surge. 100% Nylon rope doesn't come taut suddenly, but dissipates the load by stretching. It is like the difference between hitting the steering wheel or hitting the air bag. As for 100% nylon rope's resistance to ultraviolet damage, Mooring lines, particularly permanent dock lines, live in the sun. dbRopesTM lines enjoy a much longer life than other lines in that environment.