This knob worked great for my older Ryobi model 132r electric trimmer. In fact, had I waited much longer to replace it I might not have been able to get the old knob off -- there was only about 1/3" of knob remaining! But once you get a grip on it, it's easy to unscrew the old knob and thread on the new one. All the other parts on the head of the trimmer looked fine, just the knob needed to be replaced. I used it last weekend and it worked fine!