Psk pet mart size guide- xs-fit for 16 weeks to 5 months of age or up to about 5.5 lb cat. S- fit for 5.5-11 lb cat m- fit for 11-16.5 lb cat l- fit for 16.5 lb and up cat application steps- 1.Correct size is important.Take one of the nail caps out and try it on your cats claws without the glue to ensure a proper snug fit. 2.Trim cat claws to the same length with that of the nail caps. If the nail cap is too large, you may trim the open end of the nail cap until it fits. Note- do not trim kittens claws before applying nail caps. You will need a sufficient claw surface for the glue to adhere properly. 3.Fill each nail cap a little glue, only glue in a part of the nailabout 1 3, never fill to too full to prevent overflow of the adhesive, wait the adhesive is half-dried in the nail cap. Please be careful and avoid dropping glue on your hands or your cats fur, if you do, remove it with use nail varnish remover or dispergator. 4.Grasp the claws of your cat, slightly push aside the fur around the nail and expose the nail. Put the nail caps onto the claw and make sure they are completely wrapped. Wait until the adhesive is dry and continue with the next nail. 5.Observe your cat at least 5min to make sure nail caps are secure, then you have completed, we suggest you to distract your cat or feed his or her favorite food immediately after applying all nail caps. Notes- 1.Most cats will like their new claws, but some cats will reject. Generally, after wearing for the first few times, they will get used to them and without any discomfort. 2.Different cats, different movement and location such as cement, grass, floor, carpet etc., different wear rate of the nail caps. Some wearing 3-5 days may wear out. Some can wear 1-2 months or even longer. 3.Addition,the cat nails have scalability, we recommend you leave a little gap out when stick the nails, that cat nails have activity space.