Set of two Crucial 4GB RAM modules, each with a capacity of 4GB and a total of 8GB of memory. These DDR3 SDRAM modules have a form factor of DIMM and a total of 240 pins. They are ideal for replacing existing RAM modules in computers that require ECC memory. I haven't tested them but they were 100% working when I took them out of my computer years ago and have since sat on a shelf.