What happened to the Seebackwascope?

Looking at the stuff on this site, I found myself wondering, 'What happened to the Seebackwascope?' It was a wonderfully useful device that allowed you to look backwards as you walked along the street. I suppose it must have gone the way of X-ray specs. Both will have been hounded out of existence by the bureaucrats of advertising standards purely because they didn't work. How petty can you get? And, besides, I see lots of ads for banks and slimming products and they definitely don't work.