What is this?!?!?

What is this little yellow component?

I've searched all day and cannot figure out what this is. It is in a battery pack connected to 5 1.2 V rechargable Sanyo batteries. I was hoping someone out there could enlighten me.

It has the same label on both sides, and no other obvious markings.

Thanks,
Chris

That last character is an A btw.

Looks like it could be a fuse of some sort (maybe a polyfuse?) @ 2.5 Amps...?

I think you're right, I searched a little and I'm coming up with polyfuse/resettable fuse/PTC components with that same F marking on them. It does not appear, however, that the 2.5 definitely correlates to the amp rating of the component. There is more than one key amperage that can apply, holding current vs. peak current etc. I have seen components where neither of these values contribute to the nomenclature (unless of course the picture is of some other value component than the one advertised.)

Anyone have any clue whether this is the case? I'm hoping it is that simple, otherwise I may be in for some very expesive trial and error.....