If you stacked three quarters on top of each other your pile would still be about .5 mm thicker than this 4.7-mm thick light box, which slips easily into a bag or portfolio. The dimmer on this model is stepless, meaning you're not confined to preset light levels. You can gently touch it to get the perfect amount of brightness. The A4 size is equivalent to 8.27 × 11.69 inches, and a metric ruler borders the length and width of your workspace for a handy reference tool. It’s powered by a USB cable, so if you prefer an AC power source you’ll need to buy an adapter.