The NeoPixel is 'split', one half is the RGB you know and love, the other half is a white LED with a yellow phosphor. Unlit, it resembles an egg yolk. Lit up these are insanely bright (like ow my eye hurts) and can be controlled with 8-bit PWM per channel (8 x 4 channels = 32-bit color overall). Great for adding lots of colorful + white dots to your project!
NeoPixel LEDs use 800 KHz protocol so specific timing is required. On NeoPixels, the PWM rate is ~400 Hz, which works well but is noticable if the LED is moving. In comparison, DotStars have a 20 KHz PWM rate, so even when moving the LED around, you won't see the pixelation, the blending is very smooth. (we recommend DotStars if you can use them)
NeoPixels are 5050-sized LEDs with an embedded microcontroller inside the LED. You can set the brightness and color of each R/G/B/W with 8-bit PWM precision (so 32-bit color per pixel). The LEDs are controlled by shift-registers that are chained up down the strip so you can shorten or lengthen the strip. Only 1 digital output pin are required to send data down. The PWM is built into each LED-chip so once you set the color you can stop talking to the strip and it will continue to PWM all the LEDs for you.
The strip is made of flexible PCB material, and comes with a weatherproof sheathing. You can cut this stuff pretty easily with wire cutters, there are cut-lines every 0.65"/1.7cm (1 LED each). Solder to the 0.1" copper pads and you're good to go. Of course, you can also connect strips together to make them longer, just watch how much current you need! We have a 5V/2A supply that should be able to drive 1 meter (depending on use) and a 5V/10A supply that can drive up to 4 meters (depending on use) You must use a 5V DC power supply to power these strips, do not use higher than 6V or you can destroy the entire strip.
We have a tutorial showing wiring, power usage calculations, example code for usage, etc. for NeoPixel Please check it out! Please note you will need a NeoPixel library with RGBW support which is not always available. If you try to control these with a plain 'RGB' NeoPixel library, you'll get very weird results. Our Adafruit NeoPixel library does support RGBW but if you're using something else, just be aware that it might require some hacking. Also, the Blue LED element is close to the white phosphor and the light bleeds into it, so blue light will have a mix of white as well.
These strips are sold by the meter! If you buy 5 meters at a time, you'll get full reels with two connectors. If you buy less than 5m, you'll get a single strip, but it will be a cut piece from a reel which may or may not have a connector on it. If the piece comes from the end of the reel, the connector may be on the output end of the strip!