Quote from: oscarzululondon on June 15, 2012, 10:16 pmI've seen hologram stickers that change color completely from clear to red when opened which would be more discreet. It wouldn't be noticeable at all, it wouldn't protrude on the envelope, it wouldn't accidentally fall off, will always work and is obvious straight away if tampered with.An much better suggestion OZ, many thanks!V.