Good evening folks.
So full disclosure, I am not an electrician or anything close 
I have the switches in the title, and am trying to get them to work.
THe problem i have is both switches have the same wiring, and the add on switch only has spots for 3 (ground, traveler, neutral).
The main switch is working (at least i think it is, its powered on) and I have paired it with the Smart things app.
Only when I try to replace the second switch with the add on switch does it no longer work.
At the main switch i have 1 red, 2 blacks, and a green.
The blacks are Load/LIne the red is neutral and the green of course is ground.
I have the same four wires at the 2nd (add on) switch with only 3 available terminals for them.
Any advice would be great…
These switches control 12 exterior can lights.
thanks