BibBits Magnetic Race Bib Holders (Runner Design) Dimensions: 20 x 15 mm Total Weight: 20 grams BibBits are not a toy! Keep away from children. Keep BibBits away from all devices that can be damaged or influenced by magnetic fields like bank cards, credit cards etc. BibBits can influence the working of pacemakers etc. People using such devices cannot use BibBits.