This is a SK hynix (formerly Hynix) laptop memory module (RAM). Key Specifications: • Manufacturer: SK hynix • Part Number: HMT351S6CFR8C-PB (or variants like HMT351S6CFR8C-PB N0 AA) • Type: DDR3 SDRAM • Form Factor: 204-pin SO-DIMM (Small Outline Dual In-Line Memory Module, for laptops/notebooks) • Capacity: 4 GB • Speed: PC3-12800 (DDR3-1600 MHz) • Rank: Dual Rank (2Rx8) • CAS Latency (CL): 11 • Voltage: 1.5V (standard DDR3; some listings note compatibility with 1.35V low-voltage systems, but primarily 1.5V) • ECC: Non-ECC (unbuffered, no error correction) • Configuration: 16 chips (256M x 8 per side, typical for dual-rank 4GB module) It’s a common OEM module from around 2012–2013, often found in laptops from that era (e.g., compatible with many Dell, HP, Lenovo, and even some MacBook models supporting DDR3-1600). The “PB” in the part number indicates lead-free/RoHS compliance, and “NO AA” is a revision code. This is reliable for upgrading older DDR3 laptops.