What are "flex needles"?

I saw some " flex needles " in JoAnn’s yesterday and they looked similar to circulars, but had a wooden bobbin on the end. Why would you use them instead of straights?

the part of the needle that you hold on to is shorter, like on a circ, so they are easier to hold, especially if you are used to working with circs.

They’re a sort of hybrid between straights and circs, with some of the advantages of circs – the weight of the knitted piece lies in your lap instead of hanging from your arms; and you can squeeze a lot of stitches onto them.

But ever since knitters discovered that they can knit back-and-forth on circs, flex needles have become less popular.

There’s one situation I can think of in which they’d be very useful. I recently finished a sweater (from Sally Melville’s [/i]The Knit Stitch) that called for two different size needles – a 4 and a 10-- to get a special effect. I was forced to use straights, which I don’t much care for. Flex needles would have been perfect for that job.