Please be careful on putting those all natural flea collars on your cat or any pet. Trixie had one and all of a sudden clumps of fur fell out below his collar. Just because it is all natural doesn’t mean your pet will be able to tolerant it.
Cats can be allergic to something in the so called natural formula. My cat lost fur and it was scary. I took him to the vet and now he has to have medicine put on the area.
So use caution in things that are natural and also the the items loaded with chemicals.
Take your time and choose wisely. Watch and observe your pet when using anything new around him.