Application: The heavy duty M9x0.75 to 1/2-28 adapter is designed as a replacement for Sig Sauer 1911 22, GSG 1911 22, 5PK 22, and other models with M9x0.75 threads. Flat Ridges Design: The M9x0.75 to 1/2-28 thread adapter features flat ridges for easy installation and removal using a wrench (not included), improving operational efficiency. With Thread Protector: The adapter includes a 1/2-28 thread protector to safeguard the threads when no accessory is attached or during storage. Knurl Design: The 1/2-28 thread protector features a fine diamond knurl pattern, providing enhanced grip to prevent slipping and offering a clean, professional appearance. Durable Construction: Made from premium high carbon steel with a black oxide finish, the M9x0.75 to 1/2-28 adapter with thread protector resists rust and ensures long-lasting durability.