What does CAS 2.5 mean?

[Richter]

I found some Corsair 256MB PC133 that is CAS 2.5. Should I look for CAS2?

The last time I bought memory there was CAS 3 and CAS 2 that was faster. I don't remember a setting in my BIOS for 2.5. Could somebody explain please.

 

[spanky]

link

this article is about ddr, but i am sure it applies to pc133 sdr too

 

[bunker]

http://www.anandtech.com/guides/viewfaq.html?i=4