Casio case backs are typically information-rich, displaying several key markings. The module number (four digits) is usually the most prominent marking and identifies the electronic movement. The model reference number, which identifies the specific watch design and variant, is also commonly displayed. Water resistance ratings are typically present, often expressed in meters or bars, and are particularly prominent on G-Shock and dive-oriented models.
Additional case back markings often include the country of assembly (commonly Japan, China, or Thailand for Casio watches), material indicators, and sometimes patent information. G-Shock models may feature additional markings related to their shock-resistant construction. The Casio logo and brand name are typically present, and the style has remained relatively consistent over the years, though the overall case back layout has evolved.
Some premium Casio models, particularly those in the G-Shock MR-G and MT-G lines, feature more elaborate case back designs with detailed engravings and premium materials. Limited edition models may include special commemorative markings. Digital Casio watches with resin cases may have the information molded or printed on the case back rather than engraved, which can be more susceptible to wear over time.