The SSD for this kit is a 2.5" solid state drive. It features 256GB of storage capacity and fits perfectly into either the OWC enclosure or into your laptop's 2.5" drive bay. The m4 features a SATA interface that can deliver data transfer speeds up to 6 Gb/s. It provides fast, reliable and efficient data storage and retrieval. Plus, unlike traditional hard drives, SSDs feature no moving parts, providing quiet, cool and durable storage. The 2.5" form-factor and standard SATA interface make this SSD perfect for the OWC enclosure, as well as notebook users looking for the reliability of an SSD with a little added speed on top.