It measures 16mm where the strap connects at the buckle so it fits a 19mm or 20 mm strap with 3 or 4 mm taper. These are a standard taper, but be sure to measure your strap. Is made of stainless steel and in very good pre-owned condition. We have polished and cleaned it so it is ready to go. Genuine Jaeger LeCoultre men’s deployment clasp.