Now in one of the most popular sizes, we have brought a flashing led. The 3mm flashing round top blue led will automatically start flashing once it is appropriately hooked up to power. There is nothing extra needed when hooking this led up to power. A power source, led, and resistor is all you need. 6Hz = 6 cycles per second or about 360 times per minute. It will flash on and off 6 times each approximately per second. We consider this an "ultra fast" flashing LED. The frequency is approximate.We use and have only the highest quality leds out there.