Related Clues:

• Dueler's unit
• 1/500 of the Indianapolis 500
• Odometer unit
• Marathon fraction
• Duel distance
• Part of R.I.P.
• Show nervousness
• Race length, perhaps
• Square __
• Treadmill unit
• Lap, maybe
• Rate of progress
• 1,620 yards, in Old Rome
• Go back and forth
• Dueler's distance