That is the 4-watt maximum output in the quad-flash mode (it has other flash patterns available too). For reference, the other lights are a Planet Bike BRT-5 just below the RZ4, a Hotshot on the seatpost, and the Bontrager Flare bar-tip lights.

Anyway, it's not cheap at $100 but looks like good quality. If you need a self-contained high-output light that doesn't need to be aimed precisely (like, clipped to a seatbag loop or mounted on your helmet), this has potential.