AddOn 4GB DDR3 SDRAM Memory Module - For Notebook - 4 GB (1 x 4GB) - DDR3-1333/PC3-10664 DDR3 SDRAM - 1333 MHz Dual-rank Memory - 1.50 V - Non-ECC - Unbuffered - 204-pin - SoDIMM - Lifetime Warranty

This Lenovo® 55Y3717 Compatible Factory Original 4GB DDR3-1333Mhz Dual Rank x8 1.5V 204-pin SO-DIMM 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.