Full Details from Amazon.com : http://www.amazon.com/gp/product/B00AFY62BM?tag=onigi-204GB 1x4GB MEMORY RAM 4 Compaq Presario CQ58-bf9WM CQ42-158TX CQ42-258TU ddr3 sodimm204PIN SODIMM DDR3 SDRAM DDR3-1333MHZ 1PC SINGLE MODULE 8 OR 16 CHIPS