Please read the profile! Important notes are included. Purchase = Agreement. Finger cots, 2 colors (different colors are also on sale) I am an amateur, so I cannot answer detailed questions about the materials... Please understand that they are discounted accordingly. The approximate size is shown in the photos, so please use them as a reference. (※The inner diameter of the finger cot is 16mm to 17mm.) For the finger cot, you can use jump rings or C-rings that match the thickness of the groove. What is a finger cot? It is a craft tool used to open and close or hold parts such as jump rings and C-rings. Use it by putting it on the thumb of your non-dominant hand. How to use a finger cot: ・Put the finger cot on the thumb of your non-dominant hand. ・Insert a jump ring or C-ring into the groove of the ring. ・Open and close the ring by moving the cut part of the ring back and forth with flat-nose pliers or pliers. It is a very useful tool for making accessories(^^♪ Thank you for your consideration.