Where can I find part number?

Yes, Dell is very known maker of laptop (not only :)

I have Inspiron 1525 not very new but good enough for current task.
For today I can't find part number for one very easy and little detail: Power key or anything else - I don't know how it named! (see photo)

This part number not found on Dell site so what can I do?
Only ask experts (you) and I do it.

Any advice appreciated.

Merry Cristmas!