41.5mm Hollow double-sided visiblel The transparent design will bring you extraordinary feeling of mechanical automatic. Sapphire Glass Mirror: Synthetic sapphire watch glass,durable & scratch-resistantt.Case: 316L Stainless Steel Case 30mm Transparent caseback Cal.A49 10 machanical self-wind movt,Frequency 28800 v.p.hDouble way winding system,80 hours power reseverEquipped with 28 Jewels,Incabloc triangle shock absorber Exquisite mechanical hollow out. Pin buckle rubber/learther strap Pin buckle, easy to adjust and wear.Natural rubber material, soft and comfortable,waterproof and corrosion resistant.Italian cowhide leather strap, combined with German craft stiching technology, handmade oil edge, it's soft, comfortable and durable. Band Length: 180mm-230mm FEATURES Crystal: Sapphire Crystal Scratch ResistantMaterial: Stainless SteelCrown: Screw-Down CrownType: Cal.A49 10 machanical self-windWaterproof: 50m（5ATM）Power Reserve: 80 HoursHands: Luminescent How to maintain this mechanical watch? When using for the first time, please manually wind up the watch to get enough energy to keep it working well, energy dial shouldn’t exceed 35. If you wear the watch less than 8 hours a day, please manually wind up your watch to keep working well. Please avoid wearing it in hot water or under thermal steam environment, such as hot bathing, hot springs, sauna, etc. Battery free, as you wear it, it will automatically continue to wind up. If you wear it more than 10 hours a day, you won’t never to manually wind up your watch. Bosch World time Spirit Moon phase Big Bang Tourbillon Buying Options Buying Options Buying Options Buying Options Buying Options Add to Cart Customer Reviews 4.3 out of 5 stars 21 4.7 out of 5 stars 6 — 4.7 out of 5 stars 3 — 4.0 out of 5 stars 26 Price — no data — no data — no data — no data — no data $759.99$759.99 Mirror Material Sapphire Crystal Sapphire Crystal Sapphire Crystal Sapphire Crystal Sapphire Crystal Sapphire Crystal Strap Diameter 20mm 21mm 20mm 20mm 24mm 20mm Case Diameter 40mm 42mm 40mm 40mm 44mm 40mm Movement Cal.A4710 Mechanical self-wind Cal.A4610-2 Mechanical self-wind Cal.A4610 Mechanical self-wind Cal.A4610-2 Mechanical self-wind Cal.A5500 Mechanical self-wind Cal. A9001 Manual machinery Water Resistant 5ATM 5ATM 5ATM 5ATM 5ATM 5ATM Features energy reserve,skeleton waterproof, calendar，world time energy reserve, calendar energy reserve, Moon phase,waterproof 24 hours display, luminous skeleton,Tourbillon,Double way winding system