Elitebook 840 G1 - M.2 SSD - HP Support Community - 5228442
Amazon.com: HP Elitebook 840 G1 14.0 Inch High Performanc Laptop Computer, Intel i5 4300U up to 2.9GHz, 16GB Memory, 256GB SSD, USB 3.0, Bluetooth, Window 10 Professional (Renewed) : Electronics
OSCOO 256GB m.2 2242 Solid State Disk High Speed SATA3 for Hp 840 G1 G2, 9480M, Lenovo X240, X250, T440, T450, T450s, T440s : Amazon.in: Computers & Accessories
512GB NGFF M2 2242 SSD Solid State hard drive for HP EliteBook 820 G1,840/850 G1 | eBay
M.2(2280)SSD can't install HP elitebook 840 G1 i7 - YouTube