This is the ideal taillight for the urban cyclist. The light from two very bright red LEDs is spread across the width of the light.
The Toplight Line Plus uses an interesting fresnel to spread the light from two LEDs into a line across the width of the light, providing increased surface area for the light, and making it more visible at a distance.
The Toplight Line Plus has the usual standlight, and mounts to the rear of many racks. This taillight is narrower (92mm) than any other rack mount B&M taillight, making it more suitable for some of the new narrow racks. Even though the light's housing is narrow, the light you see at night is much larger than with other taillights.
There's a red tab on the bottom which you can press to switch off the standlight when you park the bike. It does this by discharging the capacitor.