They are Masses celebrated by the Society of St. Pius X (SSPX), a Traditionalist Catholic priestly fraternity whose bishops are in schism from the Church. The Masses celebrated by the SSPX are done according to the liturgical rubrics in force prior to Vatican II. Although the consecration of the Eucharist at these Masses is valid, the celebration of those Masses is illicit (i.e., unlawful) and Catholics should not attend.