Best way to store cartridges?

I've got a Denon DL-103R that I keep as a back-up cartridge. I'm considering having the the cantilever / stylus replaced, as well as having it mounted / potted in a wood body. However, as I mentioned, it's my back-up. I may not use it for years.

What's the best way to store cartridges for the long run? Air-tight container? Displace the air with N2 (not sure an easy way to do this)? Any other considerations?