The extra space under the footwear is required to accommodate the powerful, contoured electromagnet, that 10zag devices will discretely install below the instep. A power supply lead runs up your trouser leg, or is embedded in the seam of a stocking (sold separately) terminating in a small, rechargeable, remotely controlled powerpack.

Now when you walk the streets with your Street Combers in place, your shoes will pick up any small ferro-magnetic objects. Most of these will be total crap, but you gain in other subtle ways.

You can switch off your shoes at any time, mysteriously leaving behind strange little heaps of material harmlessly in the middle of otherwise pristine spaces.

The alternative is to keep on harvesting until your insteps begin to resemble a pair of hairy armpits, bristling with pins, bits of rusty nails, and other diverse pieces of metallic detritus. These can be periodically shaken into jars and a little museum collection established.

Note - not suitable for air travel