Today, April 28, is the feast day of St. Louis Marie de Montfort, whose writings had a significant influence on Matt Talbot during the last forty years of his life. The chains that were found on Matt's body after his death were part of his "Total Consecration to Mary," which was popularized by de Montford. Today, however, the wearing of a chain or medal reminding one of holy slavery to Mary is an optional practice.
Links for further reading:
one biography of St. Louis de Montfort's life