Expansion is limited to a pair of DDR3 SO-DIMM slots (16GB max), one full-size mini PCIe slot that supports mSATA SSD drives and one half-size mini PCIe slot that's perfect for WiFi and Bluetooth.
The MAINGEAR Solo 21 All-in-One offers up to 16GB of DDR3-1600 memory and supports full size hard drives up to 1TB of storage, an mSATA SSD up to 256GB for maximum storage performance, and optional eSATA for fast external storage.