A practical method of storing negatives and contact proof pages is to buy a paper (glassine) type of storage sheets.
These negative sleeves are made of finely-ground pulp paper which is largely grease-proof and water resistant. The high level of transparency is achieved by a special mechanical treatment called calendaring. Glassine sleeves are made of acid- and lignin-free photo glassine.  
Features 
Each sleeve fits 7 strips of 6 frames
Museum quality, document safe
Acid- and lignin-free
Highly suitable for archiving
Pages fit 3 ring binders 
Outside measurements: 25 x 31 cm
Pocket measurements: 4 x 21.5 cm
 

Note: Fits the Albox binder (sold separately here).