The Siemens 6ES7951-0KF00-0AA0 is a spare-part memory card for the S7-300 PLC family. It carries 64 kbyte of Flash-EPROM storage, enough for a mid-size logic block and data block set on a 5V backplane.
Memory type and lifecycle reality
Flash-EPROM means the card retains the program without battery backup and can be erased/reprogrammed in the field — standard for S7-300 CPUs that lack integrated load memory. The lifecycle stage is marked mature, which in Siemens terms means the part is no longer in volume production but remains available through the service spares channel. For BOM planning, treat it as a last-time-buy candidate: order the quantity you need for the remaining life of the line, because the official supply window may close without a direct drop-in replacement.