FANUC A20B-3900-0052 is a 512 KB SRAM memory module designed for compatible FANUC CNC systems. This plug-in DIMM provides battery-backed memory for storing CNC parameters, machining programs, and other control data. It is listed for FANUC Series 16i, 18i, 21i and 15i control systems, with compatibility depending on the specific hardware configuration. The module is suitable for CNC memory replacement or expansion. Back up all required data before replacement, as parameters and programs may need to be reloaded. [stock available]