1 Pc M.2 Ngff Ssd To For Lenovo Thinkpad X1 Carbon 20+6pin 26pin Ssd Adapter Board Card For Pc Accessories - Pc Hardware Cables & Adapters - AliExpress
Looks like m.2 2280 worked out just fine for t450s : r/thinkpad
Lenovo ThinkPad T440p 14" Laptop, Intel Core I5-4300M up to 3.3G, 12G DDR3L, 1T, DVD, VGA, miniDP, USB 3.0, W10P64-Multi Languages Support (EN/ES/FR) - Walmart.com
ThinkPad T440p SSD Upgrade with Transcend MTS400 256GB 2242 M.2 SSD – Mostly About Computers