Amazon.com: Sintech M2(NGFF) SATA SSD Card,for Upgrade 24Pin 2012 Year MacBook PRO Retina SSD (Fit M.2 SATA 2280 SSD,Not Fit M.2 nVME SSD) : Electronics
My maxed out Mid-2012 13 inch MBP - 16GB of ram and 1.2TB of SSD! : r/mac
How to Upgrade the SSD in a 15-inch MacBook Pro w/ Retina display (Mid 2012–Early 2013) on Vimeo
Teardown of Mid-2012 MacBook Air Reveals Tweaked SSD Connector - MacRumors