661-5962 Memory, DDR3 1333, SO-DIMM, SDRAM, 4 GB - 17inch MacBook Pro Early Late 2011 - A1297 NB-3823W
This is a 4GB RAM Upgrade for various Mac models that use PC3-10600 SODIMM chips.
Apple part number: 661-5962
661-5962 Memory, DDR3 1333, SO-DIMM, SDRAM, 4 GB - 17inch MacBook Pro Early Late 2011 - A1297