looks like the spacer for your tank bolt
Over 7yrs, 60K miles and reliable as ever
2004 1300S, Cobra Speedster Slashdowns, Kuryakyn Lightbar, Mustang seats, Saddlemen bags with Easybrackets, Pyle PLMCA20 speakers
Them boys nailed it. Tank spacer. Goes insie the rubber grommet, under the bolt. Keeps you from tightening the tank down solid. It allows it to "float" on the grommet.