The swing straps arrived very quickly. They are made of a high quality nylon. They do not fray and show no signs of wear after months of use. I am using them on hamock chairs that get a lot of use. My husband is about 210 and the do not show any stress when he is on the chairs. Also, they are the easiest to use. Just flip them over a branch (make sure it is a good heavy thick branch) and you're all set.
I highly recommend these. I will be getting another set to bring camping with other single swings we have.