It is absolutely fantastic to be able to grab the handle of a cast-iron pan like it's a normal pan and go about cooking without burning myself. Now that I've started using this sleeve I will never use a cast-iron pan without it and recommend everyone make this improvement in their life! Not to mention, it's much safer than using a cloth pan holder, as told by the review below.
Promising review: "We literally burned through two cloth hot handles before we stumbled upon this silicone one. Seriously, for basic safety/fire-hazard purposes, if you are currently using a cloth hot handle and have an electric stovetop, you need to switch to this one. We, unfortunately, didn't think about this until one caught on fire (I know, I know). We use our cast-iron skillet every day with this handle, and so far after six months, it is still good as new. It stays on securely, is easy to clean, and while it takes a little maneuvering to pull off of the handle, it is not difficult to pull off." —CF
Get it from Amazon for $5.99 (available in six colors).