ORIGINAL: Lenyaw

I have a set of Whelen Red TIR3 Super-LED Modules on my tour pak, that are probably what you saw.
These things are unbelievable as brake lights. Mine are set to strobe 3 quick times, pause, then strobe again, as long as you have your brake lights on. They both flash at the same time, not alternating back &amp\\;\\\\\\;\\\\\\\\\\\\\\;\\\\\\\\\\\\\\\\\\\\\ \\\\\\\\\;\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\ \\\\\\\\\\\\\\\\\\\\\\; forth. I was asked by so many riders, where I got them that I started carrying the local dealers cards to hand out.
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Here is the description from Whelen’s literature: “Tiny highly effective Super-LED encapsulated surface mount available in horizontal or vertical mount which comes standard with a single black ABS flange. Perfect for mounting wherever high intensity, warning is required. Available with 25 Scan-Lock flash patterns each with Phase 1 and Phase 2, (for simultaneous or alternating flashing lights) including steady-burn and synchronize wire. Size: 1-1/8” H x 3-5/8” W x 1-1/4” D.”
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Here is the link to the Whelen site. http://www.whelen.com/details_prod.php?head_id=12&amp\\;\\\\\\;\\\\\\\\\ \\\\\;\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\;\\\\\\\\\\\\\ \\\\\\\\\\\\\\\\\;cat_id=74&amp\\;\\\\\\;\\\\\\\\\ \\\\\;\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\;\\\\\\\\\\\\\ \\\\\\\\\\\\\\\\\;prod_id=145
edit: Ignore the stupid "\\\\\\\\\\\\\\\\" that have been added into the link or just go to Whelen.com, under the "lightheads" tab, scroll almost all the way to the bottom to find the TIR3 series.

You have to see them to believe how they light up the rear of you ride.
I highly recommend these to anyone that wants to reduce the risk of getting rear ended.
You would have to be totally blind to not see these suckers.
They were around $50-60 each.

ORIGINAL: jammerx

S7.9.4 Motorcycle headlamp modulation system
S7.9.4.1 A headlamp on a motorcycle may be wired to modulate either the upper beam or the lower beam from its maximum intensity to a lesser intensity provided that:
[blockquote]
(a) The rate of modulation shall be 240 plus-or-minus 40 cycles per minute.
(b) The headlamp shall be operated at maximum power for 50 to 70 percent of each cycle.
(c) The lowest intensity at any test point shall not be less than 17 percent of the maximum intensity measured at the same point.
(d) The modulator switch shall be wired in the power lead of the beam filament being modulated and not in the ground side of the circuit.
(e) Means shall be provided so that both the lower beam and upper beam remain operable in the event of a modulator failure.
(f) The system shall include a sensor mounted with the axis of its sensing element perpendicular to a horizontal plane. Headlamp modulation shall cease whenever the level of light emitted by a tungsten filament light operating at 3000 degrees Kelvin is either less than 270 lux (25 foot-candles) of direct light for upward pointing sensors or less than 60 lux (5.6 foot-candles) of reflected light for downward pointing sensors. This light is measured by a silicon cell type light meter that is located at the sensor and pointing in the same direction as the sensor. A Kodak Gray Card (Kodak R-27) is placed at ground level to simulate the road surface in testing downward pointing sensors.
(g) When tested in accordance with the test profile shown in Figure 9, the voltage drop across the modulator when the lamp is on at all test conditions for 12 volt systems and 6 volt systems shall not be greater than .45 volt. The modulator shall meet all of the provisions of the standard after completion of the test profile shown in Figure 9.
(h) Means shall be provided so that both the lower and upper beam function at design voltage when the headlamp control switch is in either the lower or upper beam position when the modulator is off.[/blockquote]
S7.9.4.2
[blockquote]
(a) Each motorcycle headlamp modulator not intended as original equipment, or its container, shall be labeled with the maximum wattage, and the minimum wattage appropriate for its use. Additionally, each such modulator shall comply with S7.9.4.1 (a) through (g) when connected to a headlamp of the maximum rated power and a headlamp of the minimum rated power, and shall provide means so that the modulated beam functions at design voltage when the modulator is off.
(b) Instructions, with a diagram, shall be provided for mounting the light sensor including location on the motorcycle, distance above the road surface, and orientation with respect to the light.[/blockquote]