The LKD1521 is a vibration switch manufactured by MPC Industries. It is designed to detect vibration levels above preset thresholds and to provide a signal output with minimal false alarms. It features a die-cast aluminum alloy housing, gold-plated contacts, and two adjustable sensitivity settings. The device uses a mechanical-electrical system to produce an alarm signal when the vibration profile exceeds the preset threshold. The contact output operates in either a normally open (NO) or normally closed (NC) mode. The device is designed for use in industrial and safety applications, such as detecting an overload, fault, or malfunction in machinery, or for monitoring a shaking process, such as an earthquake.