Sinclair's first home computer was the MK14, which was launched in kit form in June 1978. It was a long way from being a mass-market product. Its very name – MK standing for "Microcomputer Kit" – was indicative of its origins as a product developed by, and for, hobbyists. It had no screen but instead used an LED segment display (though Science of Cambridge did produce an add-on module allowing it to be hooked up to a UHF TV); it had no case, consisting of an exposed circuit board; it had no built-in storage capabilities and only 256 bytes of memory; and input was via a 20-key hexadecimal keyboard. Despite the limitations of the machine it sold a respectable 10–15,000 units; by comparison, the much more expensive Apple II had only sold 9,000 units in the United States, a much bigger market, in 1978. This success convinced Clive Sinclair that there was an untapped market for low-cost computers that could profitably be exploited.