The Cubi 18 sock from Castelli is mid-weight sock for thermal value but has a thinner, lower bulk design, with one exception. The sole of the sock from head to toe employs a Terry loop knit under foot for padding and extra warmth. The air space traps heat and also encourages moisture out, which is largely facilitated by a Merino wool blend knit, which adds the natural properties of the soft, comfortable wool fibers to the mix. Wool holds more heat and wicks naturally, getting moisture away from the skin.

Straight up sock construction you have come to expect from Castelli ensures that the Cubi 18 Sock is comfortable and durable. The toe and heel zones feature a tighter knit for greater wear, and sock maintains compression from the blended fabric and various directional alignment and construction. The Cubi moniker comes from the graphic design pattern on the cuff. An overlapping cube design in contrasting color adds a sporty look.