After checking and measuring with other precision instruments, it has no relation to the technical specifications mentioned in the product description (5% SWR accuracy -10% Power). As a bridge that was sent to me, it was completely unreliable as:
- at a tested power of 5W, it showed less than 0.5W on the 0-10W scale
- at various powers up to 10W, it always showed less than 1W on the measuring instrument and on the 0-10W scale
- all indications of the instrument on the 0-100W scale were 50% of the actual power, as measured with other certified power/stationary instruments.
Being a licensed amateur radio operator, I bought it for QRP portable use, but it turned out to be completely useless. I don't know if this specific unit was faulty or if it is generally an unreliable device. It was returned to dt... and I got my money back.