1U (43.3mm) chassis is commonly used in data centers for space-saving's think, however, the expandability may be sacrificed in the slim form factor. ASUS optional PIKE (Proprietary I/O Kit Expansion) meets the demand of direct SAS RAID upgrade on original servers, and what important is that it is connected through a unique slot to the server and will not occupy the slot 6 in 1U chassis, therefore no expansion capability will be given up. The ASUS unique PIKE provides customers with multiple I/O solutions. It helps upgrade from SATA storage to SAS storage directly, support various RAID function, without any other hardware upgrade. On the other hand, the PIKE kit also reduces the qualification resources for testing and inventory management efforts for customers.