We are all in search of miracles.
If a spectator could write a message on the back of their visiting card seal, and in less than ten seconds you could know exactly what was written inside the envelope - that would be a miracle.
That is exactly what you can do with The Working Performer's Sensor Envelope.
Nothing is added, nothing is taken away, no other props are required.
This envelope uses a new principle never used in this way before.
You will be truly astounded when you recieve this effect.