speed Controller for bicycle: 1.Compact, 2.Powerful, 3.Beautiful Appearance, 4.Suitable for Electric Bicycle. speed Controller for bicycle System Protection Featuretages:1. Under-voltage Protection,2.Overload Protection,3. Motor Block Protection,4. Speed Limit,5. Lose Control Protection,6. Short Circuit Protection,7. Phase Lost Protection,8. Hall Lost Protection,9. Overheat Protection.