Safelink: Extension Sounder. SAS2
Wall mounted 10-16 v AC extension sounder suitable for use with AC door entry telephone handsets Will trigger from and AC or DC source.
Not suitable for use with DC type - tone phones - will not trigger from the tone call handset . Sound output 80db @ 20cm. \nWhite surface mounting 2 part moulded housing.
Available as SAS2/A and SAS2/D.  These units have a different tone.
 
SAS2/ A - higher pitched "alarm" type sound and SAS2/ D - a lower level deeper sound. 
 
Dimensions:
120 x 90 x 40mm