The indication of size by weight for cats is very wrong. I bought the M and L sizes for a puppy cat and another adult and they got very big. Even the size M became large and the cats can remove the necklace easily. Do not use the weight table as a reference. For an adult cat I think the S size should get good.
The product is by AD, made of fabric and much more comfortable for cats than rigid cones

Good quality shorts with great cost benefit. Comfortable fabric. The inner lining is very thin, for those who expect something with a material similar to a compression shorts better adjust expectations. I have 1,81 and weight around 94kg and the size 3XL was perfect.

due to the width, the collar gets the cat stuck when going to the litter box and it gets a bit of the sand in it, so you have to help the cat there too, but that probably can't be avoided if you want the collar wide enough for the clever cat not to find a way to scratch itself through it.

I think it is comfortable enough for the animal to lay down its head on the collar as it is soft, but can't confirm as my cat is a drama queen and will keep its head Up in protest.

overall satisfied with the product/price/quality.

the S size is as described and fits right. the collar is softer than the usual plastic ones so it is more comfortable but still does the job and prevents the cat from scratching/biting itself (cheek wound, can't reach it with its hind leg or scratch itself against the wall now. good.).

if you want the cat to eat, you need to roll it up to the other side yourself first, then roll it back, so there's a bit of work, still better than taking it off completely each time though.