Gain is a scaling factor applied to individual force feedback effects or entire devices.

The gain of an entire device can be set with TDx_InputDevice::SetProperty() and the gain of an individual effect is defined by TDIEffect::Gain, which can be changed with TDx_InputEffect::SetParameters().

Gain can vary from 0 to 10000, with 0 indicating no force output at all, and 10000 indicating that the effect should not be scaled. Thus a gain setting of 5000 would indicate that the effect should be played at half strength.