Quoted from site:
"Independence Blue Cross Running Socks
Specially designed to help keep your feet comfortable on long runs and wick away moisture to prevent blisters, the IBC running socks are available to IBC members who have registered for the Blue Cross Broad Street Run.
The socks are a token of our support for both your participation and dedication to a healthy lifestyle. Look for them in your mailbox soon after the race.
Remember, we’re with you every step of the way!"