It depends if it is x0 as I dont want a low level s ram really,if it is under 200 grams it is light,my dura ace weighs about 140 grams for comparison..pics would be good of your though.
checked my cassette and cant fond any tell tale marks bar the lock ring, m760 i think but it could be non matching
it has rivets so i presume is shimano
the 5 biggest cogs are drilled
its 11-25
any help?