How to install an SSD on a 15-inch Retina MacBook Pro
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
MacBook Pro 13" Retina Display Early 2015 SSD Replacement - iFixit Repair Guide
MacBook Pro 13" (2015) - QWERTY - English Retina - Core i5 - 2.7 GHz - SSD 128 GB - RAM 8GB | Back Market