I have used the 12" and 18" ones for years. Just recently while browsing the JoAnn's web site I saw that a new 24" one has hit the market. I ordered it right away. I know a lot of quilters who look down their noses at these wonders but I wouldn't trade mine for anything. I have to lean on any ruler to prevent slippage at the far end of the cut and do so with this one.
What kind of clamp was it mentioned above? I'm interested.