![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 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)
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
![Genuine Cd03xl Battery For Hp Probook 640 645 G4 Series Cd03048xl Hstnn-lb8f 931702-421 Hstnn-ib813 931719-850 931702-171 - Laptop Batteries - AliExpress Genuine Cd03xl Battery For Hp Probook 640 645 G4 Series Cd03048xl Hstnn-lb8f 931702-421 Hstnn-ib813 931719-850 931702-171 - Laptop Batteries - AliExpress](https://ae01.alicdn.com/kf/HTB1fx6LcoGF3KVjSZFmq6zqPXXan/Genuine-CD03XL-Battery-For-HP-Probook-640-645-G4-Series-CD03048XL-HSTNN-LB8F-931702-421-HSTNN.jpg_.webp)