This RAM Pack will expand the memory capacity of your Sinclair ZX81 to 16K bytes. The ZX 16K RAM is not expandable in stages and so is supplied with the 16K of memory built in. All you have to do is plug it onto the expansion edge connector at the back of your computer. It will take its power from the existing power supply.
Important: Make sure that the computer is switched off before plugging or unplugging the interface.
(ZX81 not included)