Despite several reviews that indicated that the teeth broke off, I decided to try them anyway. I found them to be quite effective. However they do need to be used with some finesse. They feed easily down the drain, but because the teeth are backward facing, it is easy to catch them on drain parts when retracting. So when removing the snake, you have to pull it up very slowly and stop as soon as there is any resistance. Turn/rotate the length of the snake until the snagged tooth disengages and continue to pull up slowly. It works perfectly if you use it correctly. Mine brought up a mouse-sized clump of hair from my sink drain. Eeeeek!