These Enterprise Level hard drives are designed to meet servers that need fast performance. These are 10,000RPM and 15,000RPM hard drives in 3.5" and 2.5" form factors. The capacity ranges from 36, 72GB to 1TB. For large capacity hard drives such as 2TB-4TB drives, they only come in 7200RPM. Please see "Enterprise Capacity HDD" category if you are looking for 2-4TB drives.