Question about Transcend JetDrive 850

With the JetDrive 850, you only get the SSD. If you also need an external housing for your old SSD, then you have to buy the JetDrive 855. Please check on the Transcend website which SSD is compatible with your Appe device and install the latest operating system on the device (Catalina or Big Sur). JetDrive 850 needs a firmware update which was installed with High Sierra 10.13. Otherwise the SSD 850/85 will not work. Otherwise the SSD 850/855 will not be recognised. If you want to use an operating system older than Hig Sierra, you should buy JetDrive 820/825. The product name with the 5 at the end is always with external enclosure. When you install the SSD, format the SSD first to APFS/GUID (850/855) in recovery mode with the hard disk utility. Greetings and good luck

Thank you very much!