15x10 or 356x254mm envelopes are made to accept large documents or files that are larger than A4. We supply manilla brown envelopes in medium weight or heavy weight and it is the heavy weight ones that are most common.
Octopus stock 15x10 brands such as New Guardian, Plus Fabric and 5 Star amongst other makes.
We offer free delivery in Greater Manchester and Cheshire from our stockport warehouse.