Whilst Rolex is universally credited with producing and marketing the simplest and easiest to use GMT watch in the 1950’s, other swiss makers also tried their hand with varying degrees of success. However, one maker, in particular, stands out in that not only did it produce some of the earliest diver’s watches but it also crafted an equally easy to use GMT watch. Zodiac, was one of the first Swiss makers, alongside Rolex and Blancpain to produce purpose-built divers watch in the form of the “Seawolf”. Often overshadowed by the others, possibly because of its thinner case and smaller size, it can rightfully lay claim to being one of the very first. Robust and nicely made it was easily legible with unique triangular hands and markers at 3,6,9 and 12. Whilst never specifically issued to the military they were often a favourite of US soldiers and many saw active service during the Vietnam campaign. They may have only been 35mm in diameter but were extremely well made and functional watches. Buoyed by the success of the “Seawolf” Zodiac started to introduce other purpose-built “tool” watches and soon moved into aviation-themed timepieces. Fast forward to the “Aerospace”. Produced in the 1960’s, they utilised a single hand and rotating 24-hour bezel to afford the wearer a practical GMT function. Incorporating a date window at 3 o’clock and automatic movement the watches kept the same case dimensions as the “Seawolf”. Where they differed significantly, apart from the GMT function, was in the beautifully executed two-tone bezel inserts. Whilst Rolex had moved on from bakelite inserts and adopted painted aluminium inserts, Zodiac stayed true to form. The result is that you have some of the nicest bezel inserts ever made with a wide choice of colours rarely seen on other watches. Not only did you have different variants of insert colour but you also had a choice of dial colour. For this reason, early Zodiac aerospace GMT’s remain one of the more interesting watches to collect. Whilst prices have risen steadily over the last few years, in my opinion, they still remain one of the most undervalued vintage GMT watches on the market. Utilising some of the most unusual bezel insert colours ever made, they epitomise vintage style and proportions.If you avoid ones with cracked inserts and slipping cannon pinions, you will wonder why you have never thought of owning one before!