I wouldn't use 550. Due to the geometry of a hammock suspension and loss of strength at knots, it really isn't strong enough. And, it has a LOT of stretch to it. And, it soaks up water. What you want, and what is most likely in the picture is some type of braided dyneema cord. Amsteel Blue 7/64" is the most popular. Only thing is, it doesn't take knots well, so you need to splice it and/or use special hardware. I highly recommend watching Shug Emory's hammock videos on YouTube or read through the stickies on the suspension subforum at hammockforums.net.