Ampac tamper evident security envelope 220 x 305mm opaque pack of 20 product overview ampac tamper evident security envelope 220 x 305mm opaque pack of 20 kste 1 ampac tamper evident envelopes feature a tear off redemption slip which provides you with a sequential number allowing you to track or trace your envelope the double seal displays a void message if tampered with helping to keep items secure in transit this pack contains 20 envelopes measuring 220 x 305mm size 220 x 305mm se