Down Proofness Rating System
The downproofness rating system is based on the number of fibers, down clusters, and/or feathers that pass through the test pillow during the course of a thirty (30) minute test. At the end of the test the material that escaped is counted and a number grade is assigned (1 through 5).
The scale ranges from 1 (significant leakage) to 5 (little or no leakage). Below is the break down of the scale: