How many ways can SWAT rappel down from the roof of a building? What is the connection between the D-ring, the 8-ring and the rope?

Generally, it is the same method as abseiling. The figure-eight ring is a long metal ring that looks like a figure 8. The different connection methods of the rope on the ring can determine the speed and control of the descent. D-rings are somewhat similar to those used when rock climbing.

There are some other methods, which require special equipment. The kind that can be directly connected to the waist and then pounced down. It is a self-control device, somewhat similar to some telescopic key chains (that is, the one with a pull cord). kind, but they use steel wire...).

As for the connection of ropes, it refers to many different knots, each with different characteristics. For example, the figure-8 knot is used to connect double ropes in reverse, and the kind that looks like a spring. The knot (can't remember what it's called in Chinese) is getting tighter and tighter, and so on.

If you are really interested in the details, I will try to add some relevant content and pictures to my Space (I think it will take a few days), and you can take a look when you have time.