Postsafe extra strong peel and seal polythene envelopes are cheaper light and stronger these are ideal for any mail order online or ebay business features p26m and 5 pack 440 x 320mm all envelopes have secure peel amp seal closure available in clear with write on panel p24 amp p30 white opaque envelopes made from 100 polythene weatherproof burst proof tear and puncture resistant envelopes easy to write on surface accepts handwriting stamps or franking saves on postage cos