4GB KIT (2 x 2GB) For HP-Compaq ProBook Series 4230s 4310s (Intel GL40 Chipset) 4310s (Intel PM/GM45 Chipsets) 4311s 4320s 4321s 4325s 4326s 4330s 4331s 4340s 4341s 4420s 4421s 4425s 4430s 4431s 4435s 4436s 4440s 4441s 4445s 4510s (DDR3 Intel GL40 Chipset) 4510s (DDR3 Intel PM45/GM45 Chipsets) 4520s 4525s 4530s 4535s 4540s 4545s 4710s (DDR3) 4720s 4730s 4740s 5220m 5330m 6360b 6440b. SO-DIMM DDR3 NON-ECC PC3-10600 1333MHz RAM Memory. Genuine A-Tech Brand. 4GB KIT (2 x 2GB) SO-DIMM DDR3 NON-ECC PC3-10600 1333MHz RAM Memory Genuine A-Tech Memory Lifetime Warranty Toll Free Technical Support 1-866-557-4527 Designed For HP-Compaq ProBook Series. (See Compatibility List Below)