Understanding cartridges ?

Hmm...Clueless weighed in earlier with a nice post that excerpted some authoritative-sounding info relating to the system resonance formed by the compliance/mass equation, replete with his customary link I believe, but I see he must've pulled it - pending a new and improved edition, perhaps?...

So how do you determine if an arm is low/med/high mass?

"effective mass" is an arm manufacturer's spec. - just ask them.
Then read this link, & browse around all the other analog features on this site for a better understanding:
http://www.gcaudio.com/Archives/tonearmcartidge.htm

Thank you all for the great info. How important is arm/table matching? Suggestions for such, remembering small budget.
This was my post.

Thanks for the link, Bob. I'm glad I learned something about this before I purchase a second cartridge for my mmf-7. I have been able to find that the Project 9 arm is 11 grams and thus a medium mass arm. I have not been able to find the compliance rating for the shure v15vxmr that is currently mounted on the arm. Does anyone know what the compliance rating is for this cartridge?