This is the Directed 506T glass break sensor.

An audio sensor that listens for breaking glass using a microphone and a microprocessor. It analyses the frequency, intensity and timing of what it hears, which is how it tells a smashed window from a slammed door.

It catches soft breaks. A thief who knows what they're doing breaks glass quietly, with a spark plug shard or a punch, and the impact is often too gentle for a shock sensor to register. This sensor hears it anyway, which is the specific gap it exists to fill.

Worth adding alongside a shock sensor rather than instead of one. They cover different attacks.

Want shock, tilt and glass break in a single module? See the Compustar FT-DAS-II.