Ceiling Hangers shall have a steel frame formed to minimize height by supporting 11/2 x 1/2 ceiling channels on either side of a 1” nominal deflection centered spring. The spring shall be seated in an AASHTO Bridge Bearing Quality LDS Rubber Cup with a rubber bushing extending through the frame to prevent metal to metal contact between the steel suspension rod and the frame. Rubber Dynamic Stiffness shall not exceed 1.4. The ID of the bushing must allow a 30° swing from side to side before rod contact. Springs shall be factory precompressed to 70% of the assigned deflection. Hangers shall be Mason Industries 30CSCH. Submittals shall confirm AASHTO Quality and Dynamic Stiffness in addition to deflection.