This is a very simple prop balancer which is easy to use. Fit the prop hub in between the two tapered cones, then hold the two pointed ends of the shaft lightly between thumb and forefinger, let the prop settle and you should quite easily see which blade is the heavier.
There is a problem with these balancers. The do NOT have pointed ends on the shaft. They are flat ended. This makes it almost un-useable in the field. You would have to balance these on the edge of a glass or something, to use them. HK should make sure their manufacturers make the product to specification. I eventually got credit for the ones that I bought but would like to get them with the correct pointed end.