Sandor Szmutko/Shutterstock We may receive a commission on purchases made from links. E-ink might be most commonly known for e-Readers like the Amazon Kindle (and plenty of Kindle alternatives on Amazon ), but it's also spread to a whole range of cool gadgets thanks to two key advantages: low power consumption and ease of readability in sunlight. E-ink screens aren't lit from the back, instead reflecting natural light in much the same way ink on a piece of paper does. They only use power when you want to refresh the display, so for content that doesn't need to be updated often, you can get many weeks or even months from a single charge.  E-ink technology, which involves shifting a matrix of positively and negatively charged pigments, has come a long way since its inception in 1997, from monochrome to tri-color, and even full color displays. E-ink also has unique limitations in terms of features: You can get richer colors, but at the cost of contrast and refresh rate.…