

Why would anybody need a $6 plastic gizmo to attach a fender to a boat?
I will say why: Because one of the jobs of guests is removing and later reattaching the fenders in the slip. It's a simple thing, but with a couple of challenges. One is the knot or the cleat. The other is the height above water, which in my case is pretty precisely 6"--if more, the fender pops out when squeezed by the finger pier, if less, it sits wet and grows barnacles.
When assigned the fender task, guests, family, kids, leave a variety of homespun knots, some quite creative; and they are extremely cavalier in matters of height, if aware of fender height at all. A lengthy briefing on the topic-- "Nice to meet you for the first time, Maximillian, now when you place the fender, as you have agreed to, observe the distance above water, making sure it is precisely the height I have mentioned --measure with your eye, Max, make it 6 inches, not 8 or 10 or 16 or 2, otherwise I'll have to go back after you have gallantly departed and redo your work, and although you'll never know it, confide to myself that, 'Jeez Louise, I coulda done that faster myself" But no, no, that sort of lecture won't do. Eyebrows would rise. Control freak.
So, enter the Fender Tender, at $12 for two. The length of the fender line is pre-set. It clips to the lifeline, guaranteeing the height above water, and there is no need for a knot of any kind, or a creative cleating technique. Just clip the plastic on! Anybody can do it!
Yes, they look sort of stupid and unnecessary, but given all the above, maybe not.