I was originally wondering the same You only need one HS210 You need to replace EITHER the One at either End (one will be the Line end and the other the Load end) - both have 3 wires (plus Neutral) ....

I was pleased to see the 3-way dimmer has been added to the line-up with the News Release - anxious to get this as soon as it hits the market Here's another product request - a combined Fan Control...