Introduced by Shugart Associates in late1976 and was in production by early 1977. The SA 400 cost was $425.

The 400 drives were single sided with 35 tracks, later models were double sided with 40 tracks. The unformatted capacity was 3125 bytes per track for a total of 109,375 bytes. When formatted with 256 byte sectors at 10 sectors per track, the capacity was 896,000 bytes.

The wires are cut off on the back as pictured for unknown reason.