SEATTLE -- When the Mariners drew up guidelines for retiring uniform numbers, they set a high bar that so far has only been met by two players in franchise history.

There are nine inducted members in the Mariners Hall of Fame, but the criteria for retiring a number was set substantially higher to make it the ultimate honor.

The Mariners' Board of Directors is responsible for retiring numbers and to be eligible, a player must have either been elected to the National Baseball Hall of Fame and been in a Mariners uniform at least five years, or come close to election to the National Baseball Hall of Fame and spent a "substantial portion of his career" with the Mariners.

Players aren't eligible to have their number retired until they've been voted on once for the National Baseball Hall of Fame, which effectively means six years after their retirement.

Here are the two retired numbers which hang on Seattle's center field façade alongside Jackie Robinson's No. 42, which was retired by all Major League teams in 1997.

Ken Griffey Jr., CF: No. 24
Number retired: Aug. 6, 2016
Griffey became the first player who spent the majority of his career with the Mariners to be inducted into the National Baseball Hall of Fame and he was elected in a landslide in 2016, setting a new record by being named on 437 of 440 (99.32 percent) of the Baseball Writers' Association of America ballots in his first year of eligibility. Griffey spent 13 of his 22 seasons in MLB with Seattle and earned 10 of his 13 All-Star berths and all 10 of his Gold Glove Awards while with the Mariners. Griffey won the AL MVP Award in 1997. At the time of his retirement in 2010, Griffey had the sixth-most home runs in MLB history with 630, including 417 with Seattle, with a career .284 batting average, 2,781 hits and 1,836 RBIs.

Edgar Martinez, DH: No. 11
Number retired: Aug. 12, 2018
Martinez spent his entire 18-year career with the Mariners before retiring in 2004 after earning seven American League All-Star berths, two batting titles, five Silver Slugger Awards and five Designated Hitter of the Year Awards. Martinez also earned the Roberto Clemente Award in 2004. After his retirement, the DH of the Year Award was renamed the Edgar Martinez Award. When his playing career ended, Martinez was Seattle's all-time leader in games played, hits, extra-base hits, batting average, runs, total bases, at-bats, doubles, RBIs and walks, while posting a line of .312/.418/.515 with 309 home runs and 1,261 RBIs. Martinez remained an integral part of the Mariners even after his playing days with a street and in-stadium restaurant named in his honor, and he became the team's hitting coach in 2015.

Note: On April 15, 1997, the Mariners joined every team in MLB in retiring No. 42 in honor of Jackie Robinson.