This is used with the external digital pick-up to get an accurate reading. These can be simply stuck to your wheel rim, preferrably with a dab of loctite, or knocked into a disc brake bolt.
  Suitable for any Lambretta or Vespa with the external type pick up fitted to your SIP or KOSO speedometer
 
Diameter: Ø 6mm, depth: 5mm
 
Product code: LUSPKOBF010700