Certina
DS First C030.250.36.106.00— lug 19mm

The lug width of the Certina DS First C030.250.36.106.00 is 19 millimetres. This measurement represents the distance between the two anchor pins on the case lugs. You can verify it using a digital calliper or by removing the original strap and checking the marking on the lug base.

The optimal strap depends on usage: for formal and daily wear, we recommend alligator or vegetable-tanned calf leather with a satin-finished deployant clasp. For sporting or humid environments, a NATO or structured rubber strap maintains functionality and aesthetics. Ideal thickness ranges from 3.5 to 4.5 millimetres for balanced proportioning.

Strap replacement is straightforward: use a spring bar tool to compress the pins on the case lugs, then slide the old strap outward. Align the new strap's ends with the pins, release the spring bar, and ensure the strap is securely anchored. If inexperienced, consulting a professional watchmaker is advisable to prevent damage.

Any strap with a 19 millimetre lug width is compatible. We recommend artisanal full-grain leather straps (alligator, calf, vegetable-tanned calf) available in various finishes and colours. Ensure the clasp is appropriate for your wrist and that the leather thickness is coherent with the 38 millimetre case.

A full-grain leather strap of quality construction typically lasts 3-5 years with daily wear. Durability depends on: tanning quality, environmental humidity, wear frequency, and maintenance. Vegetable-tanned leathers develop authentic patina over time but require occasional conditioning. The fold zone (where the strap closes on the wrist) experiences maximum stress.