They were 20mm nylon straps that I got off the bay, which were supposed to take up to 500Kg or similar. The weird thing was that it went in the middle, 2 meters up from the crab, on a part of the tape that looked good; it had no signs of ware, cuts or whatever on it. I know that the force on the ropes can be more than you think due to the angle of the rope etc.. but it was a surprise when it went. The tea I was drinking at the time had cooled off & there was only a third of a mug left but it was till a shock when I ended up on my ar*e covered in tea... could have been worse & I always check for stones, logs & other things iunder the hammock that I would not want to land on if the rope goes or my knots fail.