Zenith
Chronomaster Original 03.3400.3610/40.C912— lug 20mm

The Zenith Chronomaster Original 03.3400.3610/40.C912 features lugs exactly 20 millimeters wide. This historical measurement dates back to the original 1969 configuration and is compatible with our handcrafted 20mm straps. To verify compatibility, measure the distance between the case lugs at the spring bar attachment point—the value must correspond precisely to 20 millimeters.

For the Zenith Chronomaster Original 03.3400.3610/40.C912 we recommend three options based on intended use: black or dark brown alligator for formal aesthetics that enhance the three-color dial, fine-grained calf in burgundy or blue tones for sophisticated color contrast, or black sport rubber for casual configurations that maintain the authenticity of the original design. Your choice should consider visual pairing with the dial and frequency of wear.

Change your Zenith's strap by gently removing the spring bar using a dedicated spring bar tool or small flathead screwdriver. Position the tool perpendicular to the spring bar, apply gentle downward pressure to compress the internal spring, then extract the spring bar completely. Repeat on the opposite lug. Insert the new 20mm spring bar into the appropriate slots on the strap, then reinsert the spring bar into the case. We recommend performing this operation on a soft cloth to prevent scratches.

The Zenith Chronomaster Original 03.3400.3610/40.C912 is compatible with all handcrafted straps made for 20 millimeter lugs. We recommend choosing straps made from high-quality leather (genuine alligator, Hermès calf, Italian nappa) or vulcanized rubber to ensure durability and moisture resistance. Avoid synthetic or faux leather straps that could compromise the premium aesthetic of this model.

A handcrafted quality leather strap for your Zenith typically lasts between 3 and 5 years, depending on frequency of wear and environmental conditions. Alligator leather, being more resistant and less porous, tends to last longer than calf. Humidity and sun exposure accelerate aging. To extend your strap's life, periodically apply protective products designed for leather, avoid prolonged water immersion, and store your watch in dry environments. We recommend a five-year service at the Casati Milano atelier.