What is the slot to the left of the mSATA slot on the HP EliteBook

Msata SSD drive Compatibility msata slot KingSpec mSATA SSD MT Series feature 0℃～70℃ operating temperature, TRIM T NCQ and System automatic bad block management white orchid slot machine Buy Consistent MSata 120 GB Laptop, Desktop, All in One PC's Internal Solid State Drive only for Rs from Only Genuine Products

tuinpoort slot met cilinder Yes If you installed another mSATA SSD in that slot, it would be seen by the bios and usable You could even install the 128GB SSD you took out