These pins are likely rare. It's not known how they were usually to be aquired, but someone sent in a fan art to Sega in 2005, and later on, these pins arrived in the mail. You can see them on the card at left (among the busy art) The card looks like the one enclosed with the 10th Anniversary box. The little documentation paper is all in Japanese so the pins must have originated there, though they were clearly sent to the USA. The pins themselves are nice, with the filled-enamel one having modern Sonic with the Sonic Team logo and the un-filled one having part of odd-walking SA1 era Sonic done in the raised texture.