Vacuum tubes, NOS RCA 5642 high voltage half wave rectifier, original boxes. Tested good on a Sencore Mighty Mite V tester. This tube requires 1.25 volts ac or dc for it's filament at 0.2 amp. The flexible leads are intended for direct connection to other components. The tube is capable of 10 kv peak inverse plate voltage and a peak plate current of 5 ma. It is designed to operate in any position. Further data specs are available online. Thank you for stopping by.