I have an 11mm Fly rope and am not a big fan of the Distel, and the other one I can't spell. I had a Posion Ivy rope before this, and the blakes hitch with a 13mm tail did not work on it. It slid. Now, I just missed around with my fly with another 13mm tail and it held!!! So I'm wondering if the tail diameter matters, does it have to be as skinny or skinnery than the rope it's used on or what. I'll have to try it with all my weight on it tommorrow after school, but from putting alot of weight on it tonight it held pretty could. Thanks for your help again.