Once you have everything operational, the Forerunner 405's complex array of features come together with aplomb. The rim of the watch face is touch-sensitive, and operates in tandem with the buttons to cycle through the menus and configure options. Most of the time, you will be working in Training mode, and here the 405 operates like a (very) glorified stopwatch. You simply press one of the buttons, then hold down the section of the rim marked Training. After the Garmin has obtained a satellite fix, you can embark on your run. Simply press the start/stop button to begin collecting data, press again to end the session or press the lap/reset button to start another round when doing circuits.
If you're using the HRM, this will be detected automatically if within a 10m range, and a data connection will be enabled without any need for further settings. Your heart rate will then be recorded alongside GPS location data. You can cycle through different views during Training mode with a stroke of the rim, showing distance, time, and pace, or heart rate, or a fully customisable combination. A trip to the menu provides modes for Running and Biking, which tailors the heart rate and speed zones accordingly, and changes the calorie consumption calculation. There's a Virtual Partner system, too, where you set the pace for an imaginary friend. The 405 then tells you how far ahead or behind you are.
But training isn't the only facility. You can use the 405 as a simple GPS locator, when hiking or running cross-country. For this mode, you can either store a location when physically there, or enter coordinates manually, although the latter is a little fiddly with the limited buttons and controls. A compass-like readout then points you in the right direction as you travel. The Forerunner 405 also has a Time/Date mode, where it functions as a watch with two zones and an alarm. This is also where you can see a progress indicator for your workouts and any training scheduled for the day.