I've never used one, and I'm not sure about all this tying off stuff. Ive heard on more than one occasion that they do as advertised. I just carry an extra knife with a long, thin blade, similar to, but thicker than a fillet knife. It works great for cutting around the anus, up through the pelvic bone, and really doesn't take much time to do. I haven't split a pelvic bone since I started carrying it! It works great for getting up and cutting the esophogus as well. Plus I have an extra sharp blade if my primary field dresser gets dull. Ymmv.