The quality level of the deformer. A value of 0 is the highest quality, 1 is a step lower, etc. It is up to the models to configure what each quality level means visually. If the quality level will be clamped to the available quality levels, so if you choose quality level 100, while there are only 3 levels, then quality level 3 will be used in this case, which represents the lowest available quality. In morph based models each quality level defines how many morph targets are active at most.