Neat! I remember feeling very, very fancy when I got my Timex/Sinclair 16K RAM pack. It used 4116 chips. I was puzzled why they'd have so many chips in the expansion instead of just using static RAM, but back then everything was pricey. Compared with the 2K of RAM the TS/1000 comes with, this was a huge amount of memory :)
And of course the ZX Spectrum main memory used only half of the chips. Sinclair could buy faulty RAM chips very cheaply, they binned them into "top half working" or "bottom half working", then put either all tops or all bottoms into each Speccy and set a solder point on the motherboard accordingly.
The Speccy used 4116s and 4164s (and later 4464s in the Amstrad versions, except the "+2"). The 4116 was used for lower RAM in 48k version, or all the RAM if you had a 16k version. The 4164 was used for upper RAM, and they were the ones that were binned for working upper and lower, and you set a jumper to select the good half to use. In the 128k "toastrack" and grey "+2" it used good versions of the 4164 for all its memory. A neat and typical Sinclair solution to saving a few bob on each unit.
