Aevig leather straps.
These straps were designed for the Aevig Valkyr but will be equally good on any sporty watch with a 20mm lugwidth.
Fashioned from oily calf leather with contrasting ivory stichting you may choose between the rally style, with holes or without holes. Padding in the middle is 4mm at the top and 3mm at the tip. The sides at the stichting are 2mm for not too much bulk around the buckle and overall sleeker style.