I bought shake weight a year ago from argos for around 20 pounds, i'd seen the commercials, read up on it and thought i'd give it a try. I wasn't expecting it to be as good as it is. It's actually a really good workout for your arms and i'll admit I was really tired after 10 minutes of it! You can feel it working and "feel the burn" in your arms every time you use it. It has a lot of advantage over normal weights as its only one instead of two for each arm and it's surprisingly lightweight.
Shake weight comes with pictures displaying different moves to do with it. I found this really useful as before buying it I wasn't aware you could do so much and work so many muscles with it. My arms have gotten significantly more toned and I can thank shake weight for that. It only takes 15-20 minutes a day for a workout with it and you can do it sitting down watching tv casually. It's a really good purchase if your looking for a reasonably priced all in one weight that really does work. I highly recommend shake weight.