This Top is in the new stretchy CS fabric of Poylester & Spandex. I bought two Black to wear under other Tops this Winter. The weather in the NW. is chilly now & am wearing them around the house. Wish there were more available in my size! I wear a Plus Size & find both the neck & arm holes very relaxed & comfortable. This is not a "Mock Neck", but in this soft fabric the neck can easily be turned over once. The sleeves are a reasonable length, not too long. Love these Tops!(GREAT PRICE, Tx)