It’s there. It’s not there. Castelli’s Invisible Socks provide a layer between your feet and your shoes. They do not impede the sun from shining on your ankles.
If you’ve seen Castelli’s other women’s-specific socks, these are no different from the toe through to the heel. They start with Meryl Skinlife yarn. The stuff is stretchy, wicks well, retains almost no moisture, and is bacteriostatic. The last is a fancy word for maximizing anti-stink qualities.
With the yarn, they work multiple knits into the sock. Mesh for the top of the foot, thicker at the toe and heel, a ribbed band around the arch to hold the socks in place, and a heel tab. The tab is there to prevent the heels of your shoes from rubbing your Achilles tendon. No friction and no tan lines above the ankle, either.
Now you see them, now you don’t. Castelli’s Invisible Socks protect your feet from your shoes without hiding your ankles from the world.