Magsafe adapter question

I just purchased a second magsafe power adapter for 15 inch MacBook
Pro. The seller said it was an 85 watt adapter for a MacBook Pro. It
is used but seems to be in good condition.

The problem is that it does not have the original sticker on it that
tells whether it is 60 watts or 85 watts. The seller said that it was
an 85 watt adapter but I would like to know for sure since the sticker
it missing.

Is there any other way to tell for sure? It has the original serial
number. Is there a way to check them some how? Is there some other
feature that will let you know what the wattage is?

Thanks,
Ted
.