I've just had a look in Google at the manufacturer's so-called specification
for the Isotron.

Very carefully, nothing is said which could cause dispute.

But there's no mention of by-far the most important characteristic -
radiating efficiency!

There's no law against NOT mentioning anything. This is precisely where the
manufacturer/trader has the advantage over a prospective gullible ignorant
customer.

Quality is a measure of conformance to the intended (as specified and
agreed) purpose.

If a buyer with a fistful of cash doesn't know what he wants he can't
complain if he doesn't get it.
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Reg.