San Diego Chargers LaDainian Tomlinson #21 jersey

✓Match the maker to the years. A Reebok jersey dates to 2001 or later, while Starter, Russell and Champion NFL jerseys are generally 2000 or earlier.

✓Confirm the player's years with that team. A jersey for a season he never played there is a later product or a custom.

✓Check uniform details against the team's history: number font, sleeve stripes and TV-number placement all changed over time (the Steelers' rounded numbers arrived in 1997, for example).

✓Look for patches that pin down years: the NFL 75th anniversary patch (1994), the Bears' GSH initials (1984 on) or the Chiefs' Lamar Hunt patch (2007 on).

✓Check the NFL shield. An eight-star shield means 2008 or later.

✓See whether the numbers and letters are sewn or screen-printed, and look for peeling, cracking or replaced numbers.

✓Ask for chest and length measurements. Jerseys were cut tighter, with shorter sleeves, from about 2000.

✓Rule out reproductions. Mitchell & Ness and other throwback lines recreate old jerseys, so read every label.