Axiom 4GB Low Power DDR2-667 ECC RDIMM Kit (2 x 2GB) for HP # 483401-B21 - 4GB (2 x 2GB) - 667MHz DDR2-667/PC2-5300 - ECC - DDR2 SDRAM - 240-pin DIMM

667 MHz of memory speed makes your computer great at multitasking RDIMM 4 GB memory allows you to have more programs open at a time 240-pin-pin DDR2 SDRAM interface synchronizes electrical and clock signals for an efficient data transfer rate