Strap for Speedmaster Professional Moonwatch Apollo-Soyuz 20th Anniversary

The Speedmaster Moonwatch 3691.50.31 is fitted with a 20mm lug width. This measurement is standard for watch straps compatible with this model in 18-karat yellow gold. To verify strap compatibility, measure the distance between the two lateral attachment points on the watch: it should fall between 19.8 and 20.2mm to ensure precise and stable insertion.

For the 3691.50.31 in yellow gold, the ideal strap is cognac-colored alligator: the leather grain accentuates the depth of the precious metal, while the tone creates a natural aesthetic balance. Refined alternatives include dark brown calf leather, shell cordovan which ages beautifully, or black calf leather for more formal occasions. Each choice should reflect your intended use and personal preference.

To change the strap, use a springbar tool or a thin knife. Position the watch on a stable surface with the lug facing toward you. Insert the tool into the narrow space between the lug and the lateral attachment, applying gentle downward pressure to compress the internal spring of the springbar. Once released, remove the old strap. Align the new strap to the two lug holes, re-insert the springbar and verify that it clicks into position with a small mechanical 'click'. Avoid sudden movements that could damage the case.

Yes, provided the strap is designed for a 20mm lug width. High-quality artisanal straps made from premium leather such as alligator, shell cordovan, or calf leather often prove more elegant and customizable than OEM straps. Always verify that the springbar is compatible (generally standard at 20mm) and that the leather is sufficiently flexible to adapt to the lug geometry without creating unusual tension.

The lifespan of a leather strap depends on the quality of the material, frequency of wear, and environmental conditions. A premium leather strap (alligator, shell cordovan, vegetable-tanned calf) can last 3–5 years with moderate daily use, or 8–10 years if worn occasionally. Frequent exposure to water, humidity, and perspiration reduces longevity. Keep the strap clean and dry when not in use, and consider rotating with other straps to extend the overall service life.