Product Description The SM-DH10A overvoltage protector by Shimano - keeps the voltage constant. This protector is included with all 6 Volt/3 Watt dynamo hubs by Shimano, but it is also available as a spare part. It ensures that the voltage remains constant and does not become too high. The SM-DH10A must be mounted on the rear light and is compatible with racks with 80 mm hole spacing as well as with 50 mm hole spacing. Specifications: Bolt Spacing: 50 mm / 80 mm Manufacturer Number: A-SMDH10A Contents: 1 x Shimano SM-DH10 overvoltage protector Manufacturer: Shimano Europe B.V. High Tech Campus 92 5656 AG Eindhoven Netherlands info@shimano-eu.com