The abbreviation DSTB stands for Dial-Side True Beat , meaning the ‘true’ second located on the dial side—a jumping second . This was a typical feature of classic marine chronometers, such as those supplied to the Royal Navy by John Arnold (1736–1799), the brand's namesake. Today, the jumping second is a rare complication in mechanical wristwatches—at Arnold & Son, it is an integral part of the product range due to its historical background.

Like most mechanical wristwatch movements, the automatic caliber A&S6203 from Arnold & Son beats at 4 Hz, meaning the balance oscillates back and forth four times per second. This equates to 8 semi-oscillations per second, or 28,800 per hour. Accordingly, the seconds hand would move 8 times per second. To ensure this only occurs once, a special mechanism is required that creates a pre-tension and acts as an additional escapement. Arnold & Son has made this jumping seconds mechanism visible on the dial. Mechanics and aesthetics thus come together in a fascinating way. The seconds wheel, mounted on a solid gold cock on the dial, is only released after 8 semi-oscillations. The large lever arm, whose counterweight is designed in the shape of an anchor (derived from the brand's full logo), is in turn mounted in a solid gold, polished, and satin-finished bridge. At its other end, it engages the seconds wheel via a ruby ​​pallet. The beneficiary of this mechanism is the golden second hand at the top, which rests second by second on one of the 60 indices of the rail scale.

The optical counterpart to the jumping seconds is the off-center opal hour and minute dial. Blued hands with skeletonized tips indicate the time. A fine frame in the color of the case separates the off-center dial from the large main dial. It features a fine grain and matches the color of the 42 mm wide and 12.95 mm high case. Arnold & Son opted for a light Ascot blue for the platinum model, while the rose gold watch has a matching mint green dial. Both are viewed through a domed sapphire crystal with an anti-reflective coating on both sides; the sapphire crystal on the caseback is anti-reflective on one side. The DSTB 42 is water-resistant to 30 metres.

The A&S6203 caliber was developed in-house at Arnold & Son and is manufactured, assembled, and adjusted there. It features a 22-carat solid gold rotor and offers a power reserve of 55 hours. The movement, visible through the transparent caseback, impresses with its fine finishes: the palladium-coated plate is grained, the beveled and grained bridges are decorated with radial Geneva stripes, and there are blued and beveled screws and circular satin-finished wheels.

Both models are limited to 18 pieces each. The DSTB 42 Red Gold Mint Green costs 42,700 Swiss francs, while the DSTB 42 Ascot Blue is available for Rs 59,84,000 (approx.)