These were pretty nice and easy to use. The only issue I had was that I could not fill my containers as much as possible because of the dip that the holder has. With popsicle sticks you can fill more wax without having to worry about it touching the wax. Also my wicks would lean a bit while in the holder, so I prefer to use clothes pin or popsicle sticks for sturdier hold. But these holders are still nice and it's all about preference.
This is very useful in our candle making. Stick the wick in the center and place the metal guide on top and set. It helps me locate where the perfect center is. I set the wick with this metal guide first before pouring the wax. Remove it when you think the wax already hardens..