The GBA-900 opts for a sportier style that is more in line with the GBD-100 and GBD-H1000. Although this makes it appear larger than the GBA-800 at first glance, the GBA-900 measures 51.3 x 48.9 x 16.6 millimeters, which is comparable to the GBD-800 (54.1 x 48.6 x 15.5 mm). There are large ventilation holes where the band meets the case, and the soft urethane band has oversized holes that double as large vents, placed close together for a precise fit. The GBA-900 weighs 61 grams.