+1 Is the cassette 9S or 10S?

If this helps at all I'm currently running my MTB with a seven speed SRAM cassette, 9S XT derailers, 9S Deore Hollowtec crankset and old school 7S Deore thumbshifters (front is friction) and everything shifts great. Chain is a 6/7/8 speed SRAM. I would match the chain to the cassette, but honestly I haven't done this enough to know if it matters.