Hi, i'm try to resell best out 3 kit of G.Skill F4-4000c18D-16GTZR.
Both sticks are good for max frequency validation, one can easy pass 5Ghz as you can see here: RULE`s Memory Frequency score: 2525.5 MHz with a DDR4 SDRAM
As far as i know not much retail stick can pass 5Ghz.
Price same as retail price here 280€ shipping included within EU (international buyers contact me)
Payment in advance with Paypal (as a friend) or bank transfer
Cheers
Franco