The OWC miniStack STX is Other World Computing’s latest iteration of their miniStack line, which has been pairing itself with the Mac mini since 2005. This latest version brings a 3.5-inch hard drive bay, a 2210 M.2 NVMe slot, and a Thunderbolt dock, which gives you three extra Thunderbolt 4 ports. These ports are where it gets its name; Storage and Thunderbolt eXpansion. This feature is especially welcome on the new 2020 M1-equipped Mac mini, which is only available with two Thunderbolt 4 ports.