Absolutely necessary if you have a Gigi wax warmer. I wouldn't even want to imagine what my warmer would look like without it. It seems like such a waste but it is imperative you get the collar. It will protect your warmer and will help keep wax from dripping down the pot.
The clean collars are a life saver! Without it, I think I would get wax all over the place. It's very useful and effective. I'm one of those people that likes to keep my stuff clean, the collars make life so much easier where I don't have to clean the warmer when I'm done.
I'm giving these a 3 out of 5 stars because you still have to clean up a bit. I use them all the time because if you don't I'm pretty sure it would be messier. They are easy to use. Just slide one in and start waxing.
I use these in my salon to keep the warmer free of product. Since it is a requirement for my inspection to have a clean wax pot, and drips of wax are extremely difficult to clean, these are a wonderful catch all for your pot!