Product review (4 stars): Simple, Somewhat Effective, Labor Intensive
I live in Colorado Springs where the winter humidity is frequently down in the teens. After purchasing six of these registers with filters, I was able to increase and maintain my home's humidity by about an additional 10-15%. However, during cold periods where outside temps stayed below freezing, I had to refill these registers about 3 times a day. I don't know about you, but all of my floor registers are not easily accessible and running around the house 3 times daily to refill the registers can become burdensome. The bottom line is that they work and have saved me the expense of a whole-house humidifier. Be aware also that the wick filters are required for the registers to work correctly, and each filter works about 90 days.