The Lenovo ThinkPad P70 Laptop Supports up to 4 Drives. (One 2.5" Solid State Drive or Hard Drive in the Primary Drive Bay and/or Two M.2 (2280) Solid State Drives in the M.2 Slots and One 2.5" Solid State Drive or Hard Drive in Optical Drive Ultrabay) Note: The second 2.5" Drive replaces the optical drive when installed. If installing the second 2.5" Drive in replace of the optical drive, you will need the 2nd HDD Ultrabay adapter p/n 01AV382 and the 2.5" Drive bracket for installation. If the 2.5" Drive was not installed from Lenovo, you will need the 2.5" Drive storage kit p/n 4XB0L63274 for installation. (Both M.2 slots support SATA and PCIe NVMe Solid State Drives)