Luth-AR A2 Rear Base Windage Knob Black. Specifications for Luth-AR A2 Rear Base Windage Knob: Manufacturer: Luth-AR Gun Make: AR Platform Gun Model: AR-15 Sight Position: Rear Front Sight Color: REAR SIGHT ONLY Rear Sight Color: Black Gun Type: Rifle Color: Black Package Contents: Luth-AR A2 Rear Base Windage Knob What firearm models does the manufacturer say Luth-AR A2 Rear Base Windage Knob is compatible with? The manufacturer suggests that Luth-AR A2 Rear Base Windage Knob is compatible with AR-15Luth-AR UR-23: A2 Rear Base Windage Knob Black