Identify tube

How does one identify tubes? There are no markings on a set I have.

qclabrat_102-14-2012 2:23am

qclabrat_1 OP Details Discussions Posts This discussion Message User 7 posts 02-16-2012 at 12:29am Copy Comment URL Report Comment Edit Delete I'm pulling them from my amp so I know they are EL34s, would there be ones with different voltages for these?