Murata OKI-78SR DC-DC Converter, 7V-36V DC Input 5V DC Output 1.5 Amp
You will get ONE DC-DC converter
The perfect replacement for the hot running linear regulator 7805 on the ZX80, ZX81 and ZX Spectrum, this will run cool and be reliable in this vintage home computer application, these devices have a Voltage Set Accuracy of ±2% max. meaning the output voltage can be within 4.9-5.1 Volts and these offer 1.5 Amps output, higher than the 1 Amp rating of the original 7805 Regulator