Quality Park Ship-Lite Expansion Envelopes, Self-Seal, White, 10 x 13, 100 per Box, (S3710) DURABLE: Made from reinforced, multi-layered, lightweight material that is more durable than traditional paper MOISTURE RESISTANT: Moisture resistant envelopes to preserve inner contents in the mail stream EXPANSION: Envelope expands up to 1-1/2" to accommodate bulky items LIGHTWEIGHT: Lightweight material can help save on postage and shipping GREAT VALUE: Conveniently packed in 100 count to reduce the frequency of repurchasing