Rival Arms RARA300001A Thread Protector 9mm Luger Black PVD 416R Stainless Steel 1/2"-28 tpi
https://www.tandktactical.com/shop/788130026670-rival-arms-rara300001a-thread-protector-9mm-luger-black-pvd-416r-stainless-steel-1-2-28-tpi-27043
https://www.tandktactical.com/web/image/product.template/27043/image_1920?unique=8b42a0f
The Rival Arms Thread Protector is CNC-Machined from 416R stainless steel billet results in superior corrosion resistance and durability.