adjustable weights......dial weights?

Granby1

I am new to myfitnesspal so not sure I am posting this right, but I just started Chalean Extreme a dvd workout program. In the dvd she has these weights where she adjusts the weights by dialing in .5 pound increments. Does anyone know about these or have recommendations? The ones I have found online are a little expensive. Any thoughts? I like the idea of not having a bunch of weights laying around. I found that they have weights where you can dial from 3 pounds to 24 pounds or 3 pounds to 50 pounds.