This is a kit of 2 x 8GB Modules suitable for Lenovo ThinkPad T420s 4170, 4171, 4173, 4174. P latform : Lenovo ThinkPad T420s 4170, 4171, 4173, 4174. 16GB kit consisting of (2) 8GB DDR3 Notebook modules that operates at speeds up to 1333 MT/s and has a CL9 latency.