Go Secure Extra Strong Polythene Envelopes are designed to be durable and tough with the polythene construction being tear resistant to help keep your contents safe when in transit. These envelopes are also water repellent to keep the internal contents free from water damage. Extra strong polythene envelope Water repellent, flexible and lightweight External dimensions: 470 x 430mm Internal dimensions: 470mm x 430mm Tear resistant Peel and seal closure Pack of 25