Below is my understanding of the history of the 2000 series which evolved into the Aquaracer series. The 2000 series was produced by TAG Heuer since the early 1980s up until 2004. There were several "models" within the series, and they were all 200 m water resistant. During this time period, TAG Heuer printed "professional" on their watch dials to indicate a quartz movement. Mechanical movements were printed with the word "automatic". In 2004, TAG introduced the "WAB" models within the 2000 series. These WAB models were the 2000 Aquaracer, with a WR of 300 m. The 2004 catalog shows two quartz watches - the WAB1110 (black dial) and WAB1112 (blue dial). Both dials have the word "professional" - again to designate a quartz movement. In 2005, the 2000 series ceased to exist and was replaced with the Aquaracer series. the WAB models remained, and automatic variants were also released (these had the word "Aquaracer" printed on the dial). There were other models introduced into the Aquaracer series, most notably the "WAF" (and "CAF") models. These were very similar to the previous "WK" (and "CK") models, but the WR was increased from 200 to 300m, and the word "professional" was replaced with "Aquaracer" on the dials of the quartz variants. The automatic variants had the words "Aquaracer Automatic" printed on the dial. Another interesting bit of information is that back then, TAG used a coloured logo (green/red) on the dial of their quartz watches, and a monochrome logo on the dials of their automatic watches. This changed over the years (some quartz watches have monochrome logos), but AFAIK only quartz watches use the coloured logo. If you really want to be nerdy, check out the TAG Heuer Model Code thread and that will explain the logic behind the model numbers.