8GB KIT (2 x 4GB) For Panasonic ToughBook Series 19 (DDR3) 31 52 (Core i3) 52 (Core i5) 53 CF-19 (DDR3) CF-31 CF-31S CF-52 (DDR3) CF-52 Mk4 CF-53JULZK1M CF-C1 S10 SX2. SO-DIMM DDR3 NON-ECC PC3-10600 1333MHz RAM Memory. Genuine A-Tech Brand. 8GB KIT (2 x 4GB) 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 Panasonic ToughBook Series. (See Compatibility List Below)