Limited Lifetime Warranty Six or Eight Layer Boards True DDR2 PC2-4200 Compliant Modules All Modules are Tested at Speed DDR2 is the next generation of DDR1 and is the newest memory standard approved by JEDEC Compatible with the following HP/Compaq Notebooks ~ HP Compaq Business Notebook nc4200 HP Compaq Business Notebook nc6220 HP Compaq Business Notebook nc6230 HP Compaq Business Notebook nc8230 HP Compaq Business Notebook nx9600 HP Compaq Mobile Workstation nw8240 HP Compaq Tablet PC tc4200 D2S512M533U64S8C4$55.00