Sapphire display casebacks are usually quite a bit thicker than normal steel ones in order to maintain the same level of water resistance. We've designed a Slim Sapphire Caseback that's 52% thinner (1.2mm vs 2.5mm!) than our normal Sapphire Caseback for the modder who wants to appreciate their movement and still want their watch to be as thin as possible. Be sure to also check out our range of rotors for that sweet c-c-combo! Caseback Specifications:Thickness: 1.2mmWater Resistance: 100m