The Cristal Laser sheet-protectors 502 and 904 from Prat are made from polypropylene and are therefore free of both acid and plasticizer (archival quality). Polypropylene sheet-protectors are considerably clearer than normal sleeves, do not discolour the presented materials even when stored for longer time periods and will not stick to the surface of the material inserted into them. It should also be noted, however, that these sheet-protectors are less resistant to scratching than those made from PVC. Both Cristal Laser 502 and 904 have successfully passed the Photographic Activity Test (PAT) which has been set up in order to judge per international standards (ISO 18916) whether a photo sheet-protector is archival quality or not.

The Cristal Laser 904 sheet-protectors fit into, among others, the Prat ring binders and the Prat presentation binders 102, 105, 202, 300 and 342. The punch holes are compatible with all the established multi-ring mechanisms including those from other manufacturers. The strip of mounting holes is strengthened with black plastic and this provides an especially secure purchase for the sheet-protectors.