I believe the GB10A uses a a pendulum affair which is sensitive to vibration.
The round "glass breakage detectors" available from Radio Shack etc for $4 to $10 or so, are the mercury switches or ("tilt switches") I was referring to. It is just a blob of mercury in a glass capsule which also contains a set of contacts. When the capsule is tilted the mercury runs down and shorts the contacts, providing a switch closure to be sent to the alarm panel.