While HDDs are commonly 2.5 or 3.5 inches wide, and most SATA-based SSDs are 2.5 inches wide by 7mm thick, NVMe drives take on a number of new form factors that allow them to fit in a variety of devices. The reduction in physical drive size seen in the M.2 form factor guarantees the future ubiquity of these storage devices. The 22 refers to the width and 30/42/60/80/110 refer to the length in millimeters. Currently, M.2 2280 supports SATA and it is also the most common NVMe SSD form factor for NVMe. As technology improves and shrinks, this may change. U.2 are more costly, high performance, and endurance storage devices typically found in data center/enterprise storage environments. With the addition of PCIe cards, these high-performing NVMe SSDs found their way into systems that had not yet adopted sockets to accommodate the M.2 form factor.