The result of this collaboration is "the world's thinnest 2.5in solid state hybrid drives."
The 500GB WD Black SSHD (solid-state hybrid drive) is just 5mm thick compared with the usual 9.5mm notebook drive. This makes it suitable for thin notebooks and other mobile devices.
The company also makes 7mm and 9.5mm SSHDs.
"By combining SanDisk's unparalleled flash memory expertise and technology with the hard drive know-how of WD, WD Black SSHDs offer outstanding hard drive-like capacity, and the slim form factor and the level of performance that you will only get with flash memory solutions."
WD vice president of client computing Matt Rutledge said "Working with SanDisk, WD realised our vision for products that combine the best of both technologies."
"WD's SSHDs are a significant achievement in the continuing SSHD/flash storage revolution."
The drives are shipping to OEM customers. There's no word yet about when or even if they will be offered at retail.