LION's line of specialty envelopes includes this 10" x 13" inter department envelopes with interoffice routing slip. Durable charcoal gray (black) security envelopes with gusset have a Velcro type closure and a full size outside pocket. These inter office envelopes are spacious enough to fit letter size file folders. Unlike the clear ones, these opaque envelopes are ideal for confidential envelopes. With an inch expansion, 10" x 13" envelopes also make great catalog envelopes. LION plastic envelopes are PVC free, acid free, archival safe, resistant to moisture & tearing. Recyclable envelopes. 6 envelopes / pack.