Related Clues:

• Sail's support
• Odometer unit
• Marathon fraction
• 1/220 furlong
• Scotland yard?
• 39+ inches, in Britain
• Race length, perhaps
• The one of fourth-and-one
• Three feet
•     Prison exercise area
• Square __
• Reading unit?
• Treadmill unit
• Meter's kin
• Lap, maybe