13" needles are designed for lever or Irish knitting; when you hold one needle under your arm, which helps you knit much faster. If you haven't tried it yet, I recommend this technique since you have much more control of your work. 

These needles are soft, light, warm to the touch and inexpensive. They are great for beginner knitters because bamboo offers some resistance to yarn but not as much as wood needles, so you don’t need to push hard to slide the stitch to the other needle. The resistance is helpful because there are less chances to drop a stitch than with metal needles. The soft bamboo helps relieve stress from hands so you can knit for hours.

They are made out of Japanese bamboo and are the most eco-friendly option when it comes to needles.