It is made of plastic, it’s help to stabilizes and aligns the PIP and DIP joints. Indications Hammer finger Butonary disorders Fractures Arthritis SIZE FINGER JOINT CIRCUMFERENCE NO: 1-2-3 4,3cm-4,9cm NO: 3-4-5 4,9cm-5,7cm NO: 5-6-7 5,7cm-6,2cm NO: 7-8-9 6,2cm-6,8cm NO: 9-10-11 6,8cm-7,4cm NO: 12-13-14 7,6cm-8,2cm Declaration of Conformity CE