You can check it with Sims2CleanInstaller. The texture file (if there is one) and possibly some description will show up when you click on that file. The texture file is often a very good indication on what type of object it is. THe clean installer also usually lists up if it is hair, makeup, object, a hack, etc...
Download and install the
clean installer, then make a test folder in your downloads folder, and put the file in there. Check only that folder, otherwise it can take a LOT of time (especially if you've got a lot of downloads).
Clean installer is also a much better installer than the default one, and gives you more control on where the files ends up. I never use the default installer anymore, seeing as it doesn't always install things properly, and for the fact that it is generally very buggy.