The grosgrain or the velcro? I used roughly 1.5 inches for the grosgrain ( with two strands coming down so that it looks like this

I also used a bbq lighter to burn the cut ends so that they would not fray. I quick pass over was enough, otherwise it will melt the material and change the shape of the cut.

velcro I used standard with that I found at a craft shop. I did it slightly different then how Blu described. I sewed the velco strips together so that I could tighten or loosen the gater on my leg. As long as it holds your socks up I say!