Callahan Button Up V Back Sweater in Cream. - size S (also in ) Callahan Button Up V Back Sweater in Cream. - size S (also in ) 50% tencel 37% rayon 13% cotton. Hand wash cold. Rib knit trim. Back button closure. CAHN-WK53. 3185. Los Angeles based brand Callahan is known for their comfy sweaters and perfect boyfriend fits. Their line is elevated by unique textures, materials, and techniques that give each piece versatility and wearability. Designed for cool girls everywhere, Callahan is inspired by effortlessly easy style.