String name for particles / additive soft particles factor

I’m trying to access the soft particles factor of the particles / additive shader in script. I’d assumed the name would be “_SoftParticlesFactor” but it’s not working

renderer.material.SetFloat("_SoftParticlesFactor", 2f);

I’ve tried “Soft Particles Factor”, “softparticlesfactor”, “_softparticlesfactor” and a few other variations. Anyone know how to correctly reference it?

Thanks.

When you select the shader file you are using and view it in the inspector the correct name for the attribute you want to change is found under properties.

Example: