Yankee Hill 2045 3-Lug Adapter Assembly 1-3/8-24 Tpi Aluminum/Stainless Steel. YHM's 3-Lug mount was designed with a 1 3/8"-24 thread and can be swapped onto your R9 or Nitro N20 Sound Suppressors. Specifications for Yankee Hill 2045 3-Lug Adapter...