The EFS-S550 was developed under the guidance of the Scuderia Toro Rosso pit crew. Solar powered operation, highly scratch resistant sapphire crystals, and 100-meter water resistance all combine to make these the ultimate in pit crew chronograph reliability. A countdown bezel also supports crew timekeeping management. It enables countdown of the time to the next scheduled event or the time remaining until a task being performed needs to be completed. The models in this lineup are available with a choice of yellow, blue, or orange highlight colors, each of which was selected to maximize viewability and sporty looks. There is also a choice of metal, resin, and nylon bands to suit individual preferences for look and fit.