This product uses LM399H as the reference component, innovatively uses USB 5V power supply, and adds secondary filtering to make the power supply purer and interference-free, small in size, easy to carry and fer, and the boost resistor and op amp use high-quality components with small temperature drift. Handheld, small size, light weight USB TYPE-C 5V 2A power supply, can be powered by mobile phone chargers and power 6.95V basic output low temperature drift, : Less than 0.5PPM/ Users can DIY, use ADR1399 (PIN TO PIN) as a reference element, the performance can be immediately stronger Two sets of voltage output 6.95V and 10V Use: to check the accuracy of the DC voltage range of the 6.5-digit multimeter Parameters: Reference element: LM399H Input voltage: DC 5V 2A Input interface: TYPE-C port Working indicator: green light Warm-up time: at least 1 hour Output interface: 4mm safety banana socket Temperature drift Less than 0.5PPM/(6.95V); Less than 1.2PPM/(10V) Working temperature: 10-35 Colour:Photo Color Material:plastic Different batches may have different silk screen printing on the label, which not affect the use Package Contents: 1 x Voltage Reference Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.