NEC / Sharp SP-RM2 Rear Display Speaker Attachment / pair of new speakers
NEC V321-2, V321-PC-CRE, V322, V423, V423-AVT, V423-PC, V423-PC-CRE, V463-PC-CRE, X401S, X401S-AVT, X401S-PC, and X401S-PC-CRE. This is the ratio of signal intensity to noise intensity.