HP ProBook 4520s Intel Core i3 M380 CPU @ 2.53GHz, 4GB RAM, 320GB HDD with Microsoft Windows 10 Professional and Microsoft Office 2010 Home & Business.
Laptop Motherboard For HP Probook 4520S 4720S HM57 Notebook Mainboard 598667-001 598667-501 H9265-1 48.4GK06.041 DDR3
New Ddr3 Memory Ram Pc3-10600 For Hp Probook 4320s 4330s 4420s 4430s 4520s 4530s 4535s 4540s 4720s 4730s 4740s 5320m 5330m - Rams - AliExpress
Memory RAM Upgrade for HP ProBook 4520s 4GB DDR3 SODIMM | eBay
A-Tech 8GB (2 x 4GB) RAM for HP PROBOOK 4520S | DDR3 1333MHz SODIMM PC3-10600 204-Pin Non-ECC Memory Upgrade Kit at Amazon.com