Strobes are the visual half of fire alarm notification, required so that a building's occupants are alerted whether or not they can hear the audible signal. They are what makes an evacuation signal accessible.
The specification that matters most is candela — the light output. Higher candela covers a larger room or a space with high ambient light; the required rating depends on room dimensions and mounting height, and most modern strobes are field-selectable across several settings so one part number covers many rooms.
Beyond candela, the choices are mounting (wall or ceiling — they are not interchangeable, and each has its own coverage table), indoor versus weatherproof, and whether the device needs to synchronise. Synchronisation matters: multiple unsynchronised strobes flashing in the same field of view can trigger photosensitive reactions, and codes limit it. If strobes will be visible from one another, use a sync module or self-synchronising devices.

Siemens ST-75-CW-WP Weatherproof Ceiling Mount Strobe

Siemens ST-75-R-WP Strobe Weatherproof Red Wall

System Sensor SEP-SPSWL-P AV Expander Plate Clear Plain

