Excellent, sturdy, and easy to install (always with a bit of experimentation)! I initially bought one to see it and then I bought a second one! I'm back after 8 months of use: The wire rope broke, as it was exposed to rain and sun. I would have liked it to last longer, obviously.

Very sturdy construction. It doesn't move with the wind. It is easy to put in and take out if you want. It contains a rope-cable inside but it is small. You will need to get another one. It is only for square umbrellas. I am very satisfied and it is definitely worth its money and more.

Good quality, it is made of aluminum so there is no fear of rusting.
The base requires a lot of force to tighten properly, it is also good to use some rubber between the clamp (e.g. an old inner tube) to prevent the paint on the railing from being damaged.
The rope is decent, metallic with a plastic coating. It is long enough to allow an opening of up to 1.8-1.9m. The base has 4 holes, of which the first one is 9 centimeters away from the railing.
Attention, it cannot be used if the railing is not square/rectangular because the base will not fit.