Eastern Orthodox crosses are also known as Byzantine crosses or Saint Olga Crosses. They are worn by Eastern Orthodox Christians, both Greek Orthodox and Russian Orthodox. In addition to the slanted footrest, Greek and Russian Orthodox crosses feature the "IC" and "XC", which are shorthand in Greek for Jesus Christ. The "IC" is the first and last letter of ISOUS (Jesus); the squiggly line indicating that this is an abbreviation. The "XC" is the first and last letter of CHRISTOS (Christ).
Some styles of Russian Orthodox Crosses have an inscription on the back: "Protect and Save" in Russian; other styles of Orthodox Crosses have a plain back.