I am not sure what they are called, but just about every tent I have ever owner has the black plastic piece with 2 holes in it and the line gets fed thru and finished with an overhand knot. You then can slide it up and down the line to adjust. I don't know what made me think of it but I realized that I don't see any of those in the forum. I am aware of the line lock and niteze and such, but haven't seen a variation like those. Do they not hold well? weight to much? or is it because they touched a tent and have cooties?