Our Polyester (Mylar) Folder Sleeves are made from crystal-clear, 4 mil archival polyester, approved by the Library of Congress for indefinite archival storage. We use Dupont inert Melinex or a suitable equivalent. Our polyester has passed the Photo Activity Test (P.A.T.) which means that items put in the sleeves with not react with polyester material. Polyester is a sturdy, crystal-clear material with a glass-like surface and archival properties that are approved by museums for indefinite storage (hundreds of years). 
We stock four categories of 'Folder' Sleeves:
First Day Covers
Negative Strips
Movie Posters
Digital Photo
These sleeves are sealed on one long side, which allows for easy document insertion and retrieval.  Once inserted sleeved contents remain in place due to the static-cling nature of polyester material.

Click on links above or Scroll down for sizes and pricing.

Polyester Protectors for 35 mm Negative Strips
Negative Strip Protectors.
1-9/16 x 9-1/4".
Holds 4 & 6-Frame 35mm Negative Strips.
Made from 4 mil Polyester (Mylar).
Comes with 1/4" lip.

Base SKU:s35mmrlip

120 Negative Strip Protectors
120 Negative Strip Protectors.
2-9/16 x 10-1/16".
Made from 4 mil Archival Polyester.
Holds both 3 & 4-frame 120 Negative Strips. 1/4" lip.

Base SKU:s120mmrlip