BAL's Lock-Arm Stabilizing Bar eliminates most trailer movement associated with existing leveling or stabilizing jacks, adapting to most crank don leveling/stabilizing jacks. Installation is a simple one time, bolt on application. Unique swivel mount works at various jack angles. Telescopic Lock-Arm travels up and down with jack for easy set up and storage. Uses 3/4 in. crank handle to lock and unlock Lock-Arm. Two Lock-Arms and complete mounting hardware include.