Case: 42mm x 12.75mm – stainless steel – sapphire crystal on front and back – 100m water resistant.Specifications of the Zenith El Primero 36’000 VpH The cut-out in the dial lets you see the beating-heart of the El Primero movement running at 36,000 vph and housed in a dynamic 42mm steel case with domed sapphire crystal and mushroom pushers. One has tone-to-tone counters while the other boasts two-tone white and charcoal grey counters. The sporty and technical El Primero Chronomaster now comes in two blue-dialed versions. The ‘open’ concept was launched by Zenith in 2003 and has become a signature for the Le Locle manufacture.