What do you guys do to store your 7x17 negatives?

I just called Superior Archival Materials to inquire about 7x17 negative storage envelopes. Although their website lists a solution, they referred me to Conservation Resources International (CRI) and told me that CRI was their source for these items. CRI said that anything to fit 7x17 would be a custom item.

I would like to have a solution like the archival poly bags that B&H and others sell. CRI will be happy to custom make me such an item, but I was wondering what others do.

Thanks for sharing your wisdom,