[le_baron]

I learned from the Breguet boutique in NY that the brand changes straps, buckles, and bracelets using a custom screwdriver set. All screwdrivers are color coded. The color key states the purpose for each screwdriver and provides the size for most--but not all--of the screw drivers. Unfortunately, the color key did not specify the screwdriver size for security screws on the rear of the lugs. That said, the gentlemen who helped me estimated that screwdriver is 0.5mm. The color key did say that the screwdriver for the "screw pin", i.e. the bar that goes through the strap and has a the screw head on the side of the lugs, is 1.2mm.