The HP EliteBook Folio 1040 G1 and G2 can be upgraded with 4Gb DDR3L 1600Hhz single-sided SODIMMs. But almost all once compatible SODIMMs are now manufactured as double-sided. The Adata AM1L16BC4R1-B1YS seem to be the only compatible modules, but very hard to find. I have found a company that can deliver these modules: www.hkwilwin.com. Although not on their website, you can email them for info. With shipping and bank fees, I paid $205 for 5 modules.