The storage drive in the Retina 2012 15-inch MacBook Pro is not a 2.5 or 3.5 inch drive, its a specialized blade SSD. [link|https://eshop.macsales.com/item/OWC/MAU3ENVOYPRO/?utm_source=google&utm_medium=shoppingengine&utm_campaign=googlebase&wickedsource=google&wickedid=CjwKCAiAhP67BhAVEiwA2E_9g-78mQHQlLabn4aUBp6tAMuQ91MaLGvnWPhFGRFzsjOXrc5XlAqHcBoC9vkQAvD_BwE&wickedid=716192503141&wcid=21787769987&wv=4&utm_term=&utm_campaign=&utm_source=google&utm_medium=cpc&hsa_acc=9360794409&hsa_cam=21787769987&hsa_grp=172166638481&hsa_ad=716192503141&hsa_src=g&hsa_tgt=pla-1437737649520&hsa_kw=&hsa_mt=&hsa_net=adwords&hsa_ver=3&gad_source=1&gbraid=0AAAAAD_cuHS2dMPUZ9jGPegq3hhejxwdf&gclid=CjwKCAiAhP67BhAVEiwA2E_9g-78mQHQlLabn4aUBp6tAMuQ91MaLGvnWPhFGRFzsjOXrc5XlAqHcBoC9vkQAvD_BwE|This] is the enclosure you want (as far as I know they're only made by OWC).