The Seagate ST-251 40MB 5.25" MFM Hard Disk Drive is a vintage internal desktop drive designed for compatibility with PCs. With a rotation speed of 3600 RPM and a storage capacity of 40 MB, this silver-colored HDD offers a transfer rate of 5 Mbps. Manufactured by Seagate, this unit features MFM technology and is ideal for those looking to add additional storage capacity to their computer system. This product is a part of the Seagate HDD product line and is a valuable find for collectors or individuals seeking a reliable internal hard drive with a compact form factor. USED - UNTESTED, Drive does spin up. Sold AS IS