This is an 18k rose gold Jaeger-LeCoultre Master Control 139.24.20. It has an alligator leather strap with an 18k rose gold folding deployment buckle, and a scratch resistant sapphire crystal with anti-reflective coating. It includes a pull out winding crown, and an exhibition sapphire display case back secured with 4 screws, and engraved with "JAEGER-LECOULTRE – 1000-MASTER CONTROL-HOURS – 5 ATM.," hallmarks, and serial numbers. The 40mm diameter solid two-body case, curved lugs, and convex bezel, are polished. The dial is silver with applied gold dart hour indices, applied Arabic numerals at 6, 9, and 12 o'clock, and around the perimeter are luminous pip hour indices on a black second/minute scale. It has gold-toned dauphine hands, a blued center sweep second hand, and there is a gold-rimmed date aperture window at the 3 o'clock position. It's water resistant to 5o meters/165 feet, and it has a 38-hour power reserve at full winding. The 8.5mm thick case, dial, and movement are all signed. This Jaeger-LeCoultre Master Control 139.24.20 has a mechanical automatic self-winding Jaeger-LeCoultre caliber 899/1 movement. It's rhodium plated, with fausses cotes embellishment, and it's constructed with 32 jewels, a single barrel, 219 components, blued screws, and a 22k gold oscillating weight. It includes a central hacking device for precision time setting, and the mechanism oscillates at a frequency of 28,800 vph (4 Hz).