Key Features . Plug and play online expansionUSB cable safety bracket a secure connectionSmart power sync helps to save powerSmart temperature control for stable operationSupports MyArchive cold backup technologyCompatible with high capacity 18TB hard disks The AS6004U utilizes a USB 3.0 connection cable. Simply plug it into any ASUSTOR NAS to complete hardware expansion! Depending on the model* ASUSTOR NAS devices can simultaneously connect up to 3 AS6004U units satisfying the high capacity storage demands of enterprise users.The AS6004U has a power sync mechanism that syncs it with the NAS\'s operation status. When the NAS enters sleep mode or powers off the AS6004U will enter into standby mode. When the NAS resumes normal operation the AS6004U will resume mounting. This function works to help users save significant power.The AS6004U features 4 hot swappable disk bays and is compatible with largest hard disks on the market. It supports RAID* and AES 256-bit encryption providing optimal data protection mechanisms..