Difference in circular needle cording?

[Lamb]

Hi!

I was wondering at the differences between circular needle cordings. I have knit extensively (and, often, annoyingly) with the basic plastic corded needles that are not that flexible or knitter friendly. I am looking now, however, at purchasing some from online and am wondering what the difference in cording is. One advertises as "hollow" and others are advertised as metal cording. I have never knit with metal corded needles before, and am interested to know if anyone has, and what they think of it? I am also curious as to the difference between hollow and not hollow corded needles?

I know that personal preference is an absolute factor in choosing the best needles, but I am not at all familiar with these two terms and am just looking for a bit of clarification.

Thanks for any info offered!

-Lamb