Signaller (alarm annunicator)

For demonstrating sound transmission in an airless room (in a 1000 ml vacuum vessel);
Battery-operated, very loud and shrill-sounding signalling device in robust housing, with on/off switch, supplied with batteries (3 x DG130-1C battery 1.5V, V13GA, LR44)
Dimensions: 64 x 32 x 20 mm
Weight: approx. 18 g

additionally recommended:
P1522-1T Sound-absorbing pad, D=80 mm