Mitsubishi Electric PLC Accessories, Memory Cassette, MELSEC-F Series, Applicable series: FX3U / FX3UC, Memory Type: Flash Memory, Memory Capacity(Step): 64,000, Note: Flash memory cassette for FX3U, FX3UC. Writable with a sequencer, battery backup not required, with writing error prevention protection switch. Can store up to 1.3 MB or source information.