Lineco Glassine Envelopes for 4x5 (1000 End Opening)These glassine envelopes are an economical way to protect prints, negatives and transparencies from fingerprints, dust and dirt. Flat single seam construction. Please note, glassine is not recommended for long term storage. These clamshell boxes feature a thumb cut for ease of access. Metal edge construction adds strength and longevity. This extensive manufacturing capability also allows us to custom manufacture enclosures for your specialized needs.