This HP Z9H55AT compatible 4GB DDR4-2400MHz Single Rank Unbuffered 1.2V 260-pin CL15 SODIMM is 100% guaranteed to be compatible with your system and to work right the first time. Adding additional memory is the best way to increase the performance of your system. All our memory is built to strict JEDEC standards to meet or exceed the Tier 1 OEM's factory requirements. Our products are also guaranteed by federal law to not affect or void OEM warranties.

• SoDIMM 4 GB memory allows you to have more programs open at a time
• DDR4 SDRAM interface synchronizes electrical and clock signals for an efficient data transfer rate
• Up to 2400 MHz speed with Unbuffered signal for playing the latest games and using heavy software