Ultra-Dry Down is free of PFCs and PFASs, which are potentially harmful chemicals.
Ultra-Dry Down is not a coating, as a continuous layer would significantly impact the loft of the down. Instead, it's a finish that's applied during the down processing stage. This finish consists of very small polymer particles that make the plumes and feathers hydrophobic.
The application of Ultra-Dry Down does not affect the loft of the down or cause clumping in any way.