The Twenty is on the Road

Awhile back, Matthew on the Kogswell Owner's Group list posted about how building a new bike made him appreciate the thinking that goes into a Schwinn Suburban.
Having the Twenty all built up, I get some of the same feeling.

The front fender is really well designed. That's my Reelight added on the Front wheel, a Nitto Technomic stem, Nashbar Moustache bars wrapped with Salsa Cork Tape, old DiaCompe quick release levers. I put on some 20 x 1.75 Kenda Tires, this past weekend and it rides much better. A Brooks B5N saddle completes it, along with a Live Free or Drive sticker from Prescott Alternative Transportation.

Raleigh Twenty

What part goes inside the yellow box?