Jaeger-LeCoultre Geophysic Observatory Series Watch .Case Material: Made of 316 stainless steel, featuring 12 ultra-bright luminous elements inside.Movement: Equipped with a modified 9015 caliber 772 automatic movement, the enlarged bridge size matches the original dimensions, providing details that are closer to the original appearance.Hands: Ultra-bright luminous.Crystal: Sapphire glass.Diameter: 41.6mm, thickness: 10mm.Strap: Made of imported Italian first-layer cowhide, featuring the original buckle.