8GB (2X4GB) MEMORY FOR HP PROBOOK 5320M 6440B 6450B 6455B 6540B 6550B 6555B | eBay
OFFTEK 4GB Replacement Memory RAM Upgrade for HP-Compaq ProBook 6550b (DDR3-10600) Laptop Memory at Amazon.com
OFFTEK 4GB Replacement Memory RAM Upgrade for HP-Compaq ProBook 6550b (DDR3-10600) Laptop Memory at Amazon.com
OFFTEK 4GB Replacement Memory RAM Upgrade for HP-Compaq ProBook 6550b (DDR3-10600) Laptop Memory at Amazon.com
8GB (4GBx2) Team High Performance Memory RAM Upgrade For HP - Compaq ProBook 4311s 5220m 6550b 6555b Laptop. The Memory Kit comes with Life Time Warranty. at Amazon.com
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HP ProBook 6550b 15.6" Widescreen Laptop - with Intel i5-520M 2.4GHz, 4GB RAM, 128GB SSD Hard Drive - Windows 7 Professional 64 - Used - Walmart.com
Review HP ProBook 6550b Notebook - NotebookCheck.net Reviews
How to upgrade RAM memory in HP ProBook 6450b, 6455b laptop - YouTube