Specifications:
The surface mount device with 4 terminals is designed for applications such as surveillance cameras, projectors, steering wheel heaters, power switching converters, and control modules. The model code is US-840 A X, where 'X' indicates the contact type that turns 'OFF' with temperature rise, and 'A' denotes Ag alloy contact material.

Dimensional Outline and Material:
The device features a contact material code and is designed for ON/OFF durability of 10,000 times or more. It supports a maximum reflow soldering temperature of 260°C and has cold resistance down to -20°C.

Electrical and Thermal Specifications:
- Insulation resistance: 100 MΩ or more (measured with a 500 VDC megger).
- Withstand voltage: 1,500 VAC for 1 minute.
- Differential temperature for OFF/ON: 15K or more.
- Initial circuit resistance: 50 mΩ or less.
- Temperature setting range: 50 to 130°C, adjustable in 5°C increments.
- Temperature tolerance: ±5°C, ±7°C for operation, and ±15°C for reset.

Electrical Ratings:
- AC: 125V, max. 5A, resistive load (min. 200mA).
- DC: 12V, max. 15A, resistive load (min. 200mA).

Additional Notes:
For specifications exceeding those listed, consultation is required.