STC 54 Acoustical Door System Security Metal Products is proud to introduce the STC 54 Acoustical Door System. This system is the perfect choice for any room where sound transmission needs to be kept to a minimum. The SMP STC 54 Acoustical Door System will help to insure the quality of sound in or outside the room won’t be affected by other noise sources. Continuous development has created an innovative product design that is lightweight and easy to install. The STC 54 Acoustical Door System includes door, frame, sounds seals, gravity glide hinges and threshold. All SMP Acoustical Door Systems have been tested at a NVLAP (National Voluntary Laboratory Accreditation Program) laboratory incorporating the latest ASTM standards.