512MB KIT (2 x 256MB) For HP-Compaq Color LaserJet Series 4650 5550 5550dn 5550dtn 5550hdn 5550n. SO-DIMM DDR NON-ECC PC2700 333MHz RAM Memory. Genuine A-Tech Brand. 512MB KIT (2 x 256MB) SO-DIMM DDR NON-ECC PC2700 333MHz RAM Memory Genuine A-Tech Memory Lifetime Warranty Toll Free Technical Support 1-866-557-4527 Designed For HP-Compaq Color LaserJet Series. (See Compatibility List Below)