How to install an SSD on a 15-inch Retina MacBook Pro
How-To: Upgrade the SSD in your MacBook Air or Retina MacBook Pro, boosting size & speed - 9to5Mac
MacBook Pro (Retina, 13-inch, Early 2015) Upgrade to NVMe M.2 SSD - YouTube
Amazon.com: 256GB SSD Hard Drive for Apple MacBook Pro Air 11" 13" 15" A1502 A1398 A1465 A1466 (Late 2013-2015) / OSX Sierra/Mac Pro A1481 : Electronics