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. Made of acid- and lignin-free photo glassine.  
 
Features 
 
Each sleeve fits 4 strips of 120 film.
Museum quality, document safe
4 frames of 6 x 4.5 cm
3 frames of 6 x 7 cm or 6 x 6 cm
2 frames of 6 x  9 cm
 
Acid- and lignin-free
Highly suitable for archiving
Pages fit 3 ring binders 
Outside measurements: 25 x 31 cm
Pocket measurements: 7 x 21.5 cm
 

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