Why should everyone have a prop balancer in their toolkit?
The clockwise rotation DAL / Surveilzone tough 6040 props are almost perfectly balanced straight out of the packet but the counter-clockwise ones are not. In this video I point out why it's sometimes important to be sure your propellers are balanced on a fixed wing or multirotor RC model - and why good static balance doesn't mean you won't still get vibrations.
I'll do another video on the correct method for balancing props rather than the "quick and dirty" method of sanding away the heavy blade -- because that simply creates static balance and won't guarantee aerodynamic balance.