1 HP ProBook 4540s laptop - Intel Core i3, 2.4 Ghz, 15.6 inch display, 8 GB RAM, 300 GB HDD, Windows 10 Family. Perfectly functional, with charger, sold as is, no claims
A-Tech 4GB Module for HP ProBook 4540s Laptop & Notebook Compatible DDR3/DDR3L PC3-12800 1600Mhz Memory Ram (ATMS322399B12034X1) at Amazon.com
Used HP ProBook 4540S 15.6" Laptop, Windows 10 Pro, Intel Core i5-3210M Processor, 16GB RAM, 240GB Solid State Drive - Walmart.com
HP ProBook 4540s Laptop - 15.6 Inch % Aegis Wireless
Review HP ProBook 4540s Notebook - NotebookCheck.net Reviews
HowTo ad extra memory to an HP ProBook 4540s Notebook PC - YouTube