The SKB iSeries Waterproof 12-Microphone Case can safely store up to a dozen microphones vertically, keeping them safe and snug even if you're out in the rain. The microphones are protected on all sides by thick foam padding.
The case also provides a generous amount of room for cables, mic clips, and anything else you might want to store in there.
This thing is built to military-grade standards, made from a high-strength polypropylene copolymer resin and a gasketed, waterproof, airtight design. You could dunk it into a pool and your mics would be ok (but we don't recommend it).
The interior of the case measures 20" long, 11" wide, and 8" deep.