models such as the TSL100 (Triple Super Lead 100 W) and combo amplifiers like the TSL122 (Triple Super Lead with 2×12-inch Celestion speakers) other product ranges use similar descriptive model numbers. Often, speaker cabinets designed to suit a particular range will give a prefix before the speaker description such as JVMC212 (JVM cabinet 2×12-inch Celestion speakers) or a suffix C to denote a combo variant of an amplifier such as the Vintage Modern 2266C (Vintage Modern 2 channel 2× KT66 valves Combo). Headphones and bluetooth speakers In 2010 Marshall started a partnership with Zound Industries to make headphones and bluetooth speakers, Zound Industries is most known for its Urbanears headphones and have a similar partnership with Adidas to make audio products for them. In August 2018, Marshall announced two smart speakers which run Amazon Alexa. The Marshall Legacy The classic Marshall Stack consists of one head containing the actual amplifier, on top of two stacked 4×12s, which are loudspeaker cabinets each containing four loudspeakers arranged in a square layout. The top cabinet has the top two loudspeakers angled slightly upwards, giving the Marshall stack a distinctive appearance. When a single cabinet is used, the complete unit is called a half stack. In the early-to-mid-1960s, Pete Townshend and John Entwistle of The Who were responsible for the creation and widespread use of stacked Marshall cabinets. Townshend later remarked that Entwistle started using Marshall Stacks to hear himself over Keith Moon's drums and Townshend himself also had to use them just to be heard over Entwistle. In fact, the very first 100-watt Marshall amplifiers were created specifically for Entwistle and Townshend when they were looking to replace some equipment that had been stolen from them. They approached Jim Marshall asking, if it would be possible for him to make their new rigs more powerful than those they had lost, to which they were told that the cabinets would have to double in size. They agreed and six rigs of this prototype were manufactured, of which two each were given to Townshend and Entwistle and one each to Ronnie Lane and Steve Marriott of The Small Faces. These new "double" cabinets (each containing 8 speakers) proved too heavy and awkward to be transported practically, so The Who returned to Marshall asking if they could be cut in half and stacked, and although the double cabinets were left intact, the existing single cabinet models