Strap for Defy El Primero 21 Black & White

The lug width of the Zenith Defy 49.9007.9004/11.R923 is 23mm. This measurement represents the internal distance between the two lugs of the ceramic case. A strap with a 23mm lug width will fit perfectly into the ceramic attachments without lateral play. To verify compatibility, measure the internal distance between the lugs of your watch before ordering a replacement strap.

There is no single 'best' strap in absolute terms, but rather choices oriented to your intended use. For formal contexts, we recommend medium-grain alligator in neutral or black tones, which contrasts elegantly with the ceramic case. For a warmer, more organic aesthetic, veined calf leather at 1.3–1.5mm thickness introduces humanity to the watch's imposing proportions. For sports and technical wear, satinated FKM rubber or canvas NATO straps emphasise the chronograph's functional character. Vegetable-tanned leather develops a beautiful patina over time, ideal if you desire a strap that ages gracefully alongside your watch.

Remove the watch from your wrist and place it on a soft surface such as leather or cloth. Use a dedicated spring bar tool to gently compress the internal spring of the lower lug attachment, release the pin, and slide out the old strap. Insert the new strap by first threading one end into the lug, then compress the spring on the opposite attachment and position the pin correctly in the slots. Ceramic is resistant to light scratching from tools, but avoid direct impacts. If you prefer to avoid any risk, the Casati Milano atelier can perform the change under your supervision.

Yes, provided the strap has a compatible 23mm lug width. High-quality artisanal aftermarket straps, crafted by specialised makers, fit perfectly onto the ceramic lugs. Ensure the thickness is proportionate (1.3–1.5mm for leather, variable for technical materials) and that the spring bars are positioned correctly in the lug slots. Avoid economical mass-produced straps that may exhibit inadequate construction tolerances.

A high-quality artisanal leather strap, made from noble materials such as alligator or calf, typically lasts 3–5 years with daily wear, provided proper maintenance is observed. Exposure to sweat, humidity, and UV radiation accelerates aging: treat your strap periodically with leather-specific balms, avoid prolonged immersion in saltwater, and store the watch away from direct sunlight when not in use. Artisanal straps from Casati Milano include an 18-month guarantee and are crafted from carefully selected leathers for enhanced longevity.