I purchased this tool, because I liked the overall concept of it's design and function. Having finally had a chance to use it, I found it to work extremely well, with the exception that it doesn't provide a tight seal around the bleeder screw. On almost each pull of the brake lever, I would get a minor bit of seepage from under the tool. Fortunately out of habit, I had placed rags around the base of the bleeder screw, and I was able to soak up the fluid that leaked out (followed by a quick flush of water from a spray bottle).
Having only used the tool once, I can't attest to it's durability. If the leaking doesn't get worse, the tool is still usable for me. However, if the seal becomes worse, then it's utility will quickly disappear.
The tool itself is a good concept, but the handle is too short and I found that it leaked fluid when I opened the bleeder valve. I will probably try it again next time I bleed my brakes to confirm. Bottom line though is it got the job done.
This tool works great for bleeding the brake on your bike and keeping the mess down. However, the handle is too short, and that's why its getting 4 stars. It could really use a full size handle for leverage.
This is the second faulty brake bleeder I have purchased from Rocky Mountain and I am not happy, I think I will give up on these and go back to the old manual way of bleeding. The problem is that the check valve does not work. So it ends up bing an expensive bit of hose.