Strap for Flagship 35.6 Automatic Stainless Steel Black Diamond

The lug width of the Longines Flagship L4.774.4.57.6 is 18 mm. This dimension is measured as the net distance between the two lugs (the metal appendages of the case that support the strap). To verify this measurement, use a calliper or ruler positioned on the inner face of the lug between the two contact points. This proportionate measurement is consistent with the case diameter of 35.60 mm.

For the Longines Flagship L4.774.4.57.6, we recommend straps in alligator with regular grain (dark brown or black) to emphasise the classic 1960s heritage, or vegetable-tanned calf leather that ages elegantly with warmer tones over time. For those preferring sportier materials, FKM rubber or fine-grained silicone maintain coherent visual proportions. Shell cordovan remains the supreme choice due to its natural density and the patina that develops over years, perfectly in line with the concept of temporal investment that the Flagship represents.

To change the strap on the Longines Flagship L4.774.4.57.6, you need a specific tool for spring bar extraction (spring bar tool). Position the watch on a soft base (felt or cloth) with the lug facing you. Insert the flat end of the tool under the lug, pushing gently to release the compressed spring bar. Once the spring bar is extracted, the strap will come off. To install the new strap, align the holes with the spring bars and compress the bar until you hear a click. If unsure, contact a professional: Casati Milano offers this service by appointment.

Yes, the Longines Flagship L4.774.4.57.6 is fully compatible with aftermarket straps with an 18 mm lug width. It is important that the strap has the same spring bar holes and that the width corresponds exactly to 18 mm. Online you will find a selection of 18 mm straps ready for purchase, customisable in size, initials and stitching thread colour. If you want a completely bespoke strap, Casati Milano creates custom straps with direct leather selection and 18-month warranty.

The lifespan of a leather strap depends on the material, frequency of use and environmental conditions. An alligator or shell cordovan strap can last 5-10 years with daily wear, developing a patina that increases its aesthetic character. A calf leather strap with vegetable tanning generally lasts 3-5 years before requiring replacement, also thanks to natural ageing that makes it softer and more adhering. FKM rubber straps have a similar lifespan (4-7 years) and require less maintenance. All straps made by Casati Milano include an 18-month warranty against manufacturing defects.