... , railway crossing, commercial premise, apartment block accessFunctions/features:Manual releaseMachine core with compression spring, effectively avoids the accidents caused by spring ... : straightMaximum boom length: 3, 4.5, and 6mBoom dimension: 45 x 80mmBoom weight: 3, 4.5, and 6kgVoltage: 220V ±10%, 110V ... grade: IP44 Automatic Boom barrier for parking lot and toll system