"A chasuble is the sleeveless outer vestment worn by the celebrant at Mass. Its color is prescribed according to the seasons of the Church or the particular feast being celebrated. It is typically made of silk or other rich fabric and is sometimes heavily ornamented."
—from page 74 of Treasure and Tradition: The Ultimate Guide to the Latin Mass by Lisa Bergman
This chasuble is worn by the priests of the Fraternity of Saint Peter (FSSP) who serve at Saint Benedict's Parish in Chesapeake, Virginia USA.