Insert for Shower Handle Knob to grip valve stem

My shower knob stopped working because it was made of polyacrylic and had to grip onto a brass valve stem. Over time, the teeth of the plastic shower handle wore off because the brass was much harder. This insert replaces the teeth on the inside so that the knob will once again grip the valve stem. It has twelve teeth, about 30 degrees apart, with about 8.65 mm inner diameter and about 9.6 mm outer diameter. The outside of the part is 10mm in diameter so that a new knob can be drilled out of an