Here

@akah_2019  That just refers to what Dell sold with the system. Class 40 isn’t any sort of industry standard. You’d want to check the physical size spec that your system can handle. Most M.2 SSDs are the 2280 size (22 mm x 80 mm), but again check what your system supports before buying anything.

 This is taken from the product specifications page. So which SSD ssd should I buy?