Harmonic balancer

They make a tool that doesnt require bolting on to anything, spring loaded and wont slip. The other tool in pic is damper install tool. If you hold damper by bolts while tightening down, it is hard in crank key as it puts it in a bind before its fully tightened while correct tool will pull it on without rotational torque load.
And yes, I know, you can use a crowbar and a brick and its been working fine for 12 years, just showing whats actually available for those that care to do it with tools designed for the job. You can rent both at parts stores if you dont have $100 for the pair from a tool truck.