Limited edition of 300 pieces sinn watch u212 s e leather sinn watches were the very first pioneers to manufacture proficient divers timepieces that complied with european diving equipment standards and since then have been excelling in their field of expertise the u212 is limited to 300 pieces and is the largest diving watch from the brand to date 47mm in diameter the complete piece is made from black hard coated high strength and seawater resistant steel from german submarines the cap