These are replacement hammer faces for different soft hammers and mallets that use screw on replacment heads. There are 2 variations here one that has a 1/2-13 threaded hole & one that has 3/8"-16 threaded holes. These should be printed with TPU . I used Overture TPU 95A and it has held up to appropriate useage so far. I have included .stp files so you can remix them to suit your needs.