"BWs" feature a "fly-back" mechanism, so that when the chronograph is reset to zero, it immediately begins running again, to time the next segment or event. Automatic chronographs In the mid-1960s, Heuer partnered with Breitling and Hamilton (and in competition with Seiko and Zenith) to introduce an automatic chronograph. These projects were conducted in secret, as none of the competitors wanted the other companies to be aware of their efforts. Heuer-Breitling-Hamilton held press conferences in Geneva and New York, on 3 March 1969 to show their new lines of chronographs. Heuer's first automatic chronographs were the Autavia, Carrera, and Monaco. These were powered by the Cal 11 and Cal 12 movements (12-hour chronograph); Cal 14 movement (12-hour chronograph and additional hand for GMT/second time-zone) and the Cal 15 movement (30-minute chronograph). The winding crown was on the left, with the pushers for the chronograph on the right. The earliest of Heuer's Cal 11 chronographs (from 1969) were named "Chrono-Matic". In the early-1970s, Heuer expanded its line of automatic chronographs to include the Daytona, Montreal, Silverstone, Calculator, Monza, and Jarama models, all powered by the Calibre 11 movement. 1970s In 1975, Heuer introduced the Chronosplit, a digital chronograph with dual LED and LCD displays. Later versions featured two LCD displays. Heuer began using the Valjoux 7750 movement in its automatic chronographs, with the Kentucky and Pasadena models (both introduced in 1977). The Valjoux 7750 movement was a three-register chronograph (with seconds, minutes, and hours), that also offered day/date windows. In the mid-1970s, Heuer introduced a series of chronographs powered by the Lemania 5100 movement. The Lemania 5100 movements have the minute hand for the chronograph on the center pinion (rather than on a smaller register), greatly improving legibility. The Lemania 5100 movement is considered very rugged and has been used in a variety of chronographs issued to military pilots. There are ten models of Heuer chronographs powered by the Lemania 5100—Reference 510.500 (stainless steel), 510.501 (black coated), 510.502 (olive drab coated), 510.503 (pewter-coated), 510.511 (Carrera dialed acrylic crystal PVD finish), 510.523 (Carrera dialed acrylic crystal stainless steel), as well as models with the names Silverstone (steel case with black dial) and Cortina (steel case with blue dial); the Reference 510.543 was made for the A.M.I. (Italian Air Force) and a special edition (with no reference number marked on the case) was made for AudiSport. 1980–present TAG Heuer formed in 1985 when