Flashing red lights are generally illegal and reserved for emergency vehicles. Pulse skirts this by claiming it's not a flashing light, but a pulsing one.
"Pulse is the only pulsing third brake light that meets regulatory requirements for use in all 50 states. Step on the brake pedal and Pulse goes to work pulsing, rather than flashing, the third brake light. What’s the difference? NHTSA regulations restrict flashing lights to emergency vehicles. Our award winning rear-end collision deterrent technology causes the third brake light to remain steady burning, even while the light pulses."
"Pulse is the only pulsing third brake light that meets regulatory requirements for use in all 50 states. Step on the brake pedal and Pulse goes to work pulsing, rather than flashing, the third brake light. What’s the difference? NHTSA regulations restrict flashing lights to emergency vehicles. Our award winning rear-end collision deterrent technology causes the third brake light to remain steady burning, even while the light pulses."