I have been impressed with these guylines. I purchased them to use with a hammock/rainfly set up when i go lightweight in the backcountry and have really liked them. They have held up through some pretty severe storms and when any light hits them they are extremely visible!!
"Great length, strength and visibility with built in adjustable locking slides"
I bought these to add to my tent and despite being black, they are very easy to see at night. They even helped me find my tent in the dark one night when all I could see was the reflection of the lines. They are easily adjusted and are very sturdy. They are also pretty long which is nice when I need to tie off to a high branch or large object.