ECC LOAD REDUCED UPGRADE: This type of memory is used in Workstations and Servers. It will NOT be compatible with standard desktop computers. Also, it cannot be mixed with UNBUFFERED -or- ECC REGISTERED memory. OWC 128GB UPGRADE: Consists of a single 128GB DDR4 2933 PC4-23400 CL21 4Rx4 288-pin 1.2V ECC Load Reduced DIMM Memory RAM Module Upgrade compatible with HP Apollo models 4200 Gen10 And 6500 Gen10. INDUSTRY LEADING: Consumer-friendly Advanced Replacement Program and Limited Lifetime Warranty, which includes Free Tech Support by Other World Computing. MAXIMIZE YOUR SERVER: With OWC's ECC Load-Reduced Server Memory, you will extend the life of your old infrastructure or save money when building a new one. Replacement for HP part numbers P19047-H21 P19047-K21 P19047-B21 P18455-B21 P11057-1A1 P11057-0A1 P11040-K21 P11040-H21 P11040-B21.