![What are these 2 black slots on the back of the laptop called and what is it used for? Laptop is HP ProBook 645 G4. : r/whatisthisthing What are these 2 black slots on the back of the laptop called and what is it used for? Laptop is HP ProBook 645 G4. : r/whatisthisthing](https://preview.redd.it/qty0g197dh371.jpg?auto=webp&s=e0c222f5d1d3eac653bf0a5f8b3d4cc1fa931d48)
What are these 2 black slots on the back of the laptop called and what is it used for? Laptop is HP ProBook 645 G4. : r/whatisthisthing
![HP ProBook 645 G4 - Smart Buy - 14″ - Ryzen 3 2300U - 4 GB RAM - 500 GB HDD - Notebook | Enterprise, Government, and Educational Technology HP ProBook 645 G4 - Smart Buy - 14″ - Ryzen 3 2300U - 4 GB RAM - 500 GB HDD - Notebook | Enterprise, Government, and Educational Technology](https://racksimply.com/wp-content/uploads/2020/06/2c9dabef-114f-44c6-9fc7-0d56def58c62-2-2048x1536.jpg)
HP ProBook 645 G4 - Smart Buy - 14″ - Ryzen 3 2300U - 4 GB RAM - 500 GB HDD - Notebook | Enterprise, Government, and Educational Technology
![HP ProBook 645 G4 14" Notebook - Ryzen 5 PRO 2500U - 8 GB RAM - 256 GB SSD - Natural Silver - Windows 10 Pro - AMD Radeon Vega Graphics - 10.25 Hour Battery Run Time 7AH92USABA 193905149773 HP ProBook 645 G4 14" Notebook - Ryzen 5 PRO 2500U - 8 GB RAM - 256 GB SSD - Natural Silver - Windows 10 Pro - AMD Radeon Vega Graphics - 10.25 Hour Battery Run Time 7AH92USABA 193905149773](https://www.compsource.com/mscs_images/epics/large/1059262314.jpg)