Bus connection hardware for PRL4,PRL4A,PM4 Panelboards. Mounts one (1) MDL,HMDL,MA,HMA,MC,HMC frame circuit breaker.-Kit # MD4K replaces OEM KPRL4MD. All kits come complete with detailed safety and installation instructions and include all necessary screws, brackets, and a deadfront cover plate. If additional 25" wide blank filler plates are needed see BFP1CH, BFP2CH and BFP3CH