BUY M4T28-BR12SH1 https://www.utsource.net/itm/p/1431163.html
TIMEKEEPER SNAPHAT Battery & Crystal
Description: The M4T28-BR12SH1 is a 4-pin DIP (dual in-line package) battery-backed memory module from STMicroelectronics. It stores two 128-bit words of non-volatile memory and can be used to store power-on configurations or similar applications. Features: Battery Backup: The module is provided with back-up battery power for up to 10 years Non-volatile Memory: Two 128-bit words of non-volatile memory that can be used to store power-on configurations or similar applications Dual in-line Package (DIP): The module has a 4-pin DIP package Low Power Consumption: Has low power consumption of only 1 mA Application: This battery-backed memory module is used in various types of applications such as power-on configurations, control settings, and data storage. It is also used in medical, automotive, telecom, and military applications. (For reference only)