First...nice pic there Sam. They ask for riders weight(nothing about bikes weight), what eye to eye length you want, progressive or linear spring, longer stroke length/shorter stroke length. Extra cost items include ti nitrite on the shaft, ride height adjustment and some others. If I remeber correctly you can also get it in a piggy back design with adjustable compression. Mine have 30 clicks of rebound adjustment. I fit them on the bike Sunday...I'll take some pics tomorrow. They went on nicely though I had to cut a very small "window" in the chainguard for clearence. You can't see it when the shock is mounted.