CP 010.54 are ideally sized for sending A4 and slightly-over-A4 sized items like artwork, electronics, frames and books that require protection to stay flat in the post. Our only Rigid All Board Envelopes with a white finish measure 250mm x 351mm externally and offer pre-creased options for a variable capacity of up to 35mm. White E-flute corrugated card creates a rigid reinforced structure with an internal area of 235mm x 340mm x 35mm* at maximum depth. Each envelope is an all-in-one solution that is easy to adjust and seal, with an integrated peel and seal adhesive strip for faster packing. The permanent seal keeps higher value goods safe and secure in transit and an easy open tear strip helps customers open their package quickly and easily. The white finish of these envelopes is ideal for adding branding or marketing messages and creating a clean, professional image. *Effective size decreases with increasing thickness