Enhance Your Bicycle Lighting System with the Herrmans H-Black MR4/8/Pro Dynamo Back Cover with On/Off Switch Upgrade your cycling visibility and safety with the Herrmans H-Black MR4/8/Pro Dynamo Back Cover featuring a built-in On/Off switch. Designed specifically for Herrmans H-Black series front lights-including the MR4, MR8, and Pro models-this replacement back cover ensures optimal performance and seamless functionality.