Arlen Ness 18-991

The Inverted air cleaners forged billet design maximizes airflow by pulling in air from all directions including the face of the air cleaner. Each performance air filter features an inverted pleated top and is handmade from black oiled cotton filter element wrapped in a stainless steel mesh

• 15-Spoke Design 
• Designed inspired by factory prodigy wheels found on late Touring models
• Patented backing plate technology (US Patent: US 10,851,741 B1)
• High performance black oiled cotton air filter  
• CNC machined from forged billet aluminum 
• Patent-Pending oil catch / reservoir 
• Increases horsepower, torque & mileage 
• Eliminates oil blow-bye on M8 engines 
• Finish: Black anodize 

FORGED BILLET ALUMINUM BACKING PLATE:

• CNC machined from forged billet aluminum 
• Features Patent-Pending next generation hidden breather technology. Each hidden breather is o-ringed at the heads, passes through the backing plate and exits inside the mouth of the throttle body through proprietary shooter tubes. This eliminates the need for any external hoses or hardware for a virtually closed loop system 
• Radius air inlet for unobstructed airflow
• Specially designed breather bolts are hidden under billet covers for a clean look 
• Eliminates oil blow-bye issues associated with M8 engines by directing any excess breather oil back into the engine 
• Patent-Pending Oil Catch / Reservoir. To ensure no oil saturates the filter and restricts your airflow, the integrated oil catch collects any excess engine oil before it reaches the air filter. Bolt-on design allows oil catch to be serviced when you service the filter element 

Replacement Filter: 18-938

INVERTED PERFORMANCE AIR FILTER:

• Each Inverted Series filter is handmade in the U.S.A.
• Features an inverted pleated top and full perimeter pleated sides to pull in air from every direction 
• Made from black Synthetic filter element that is wrapped in Stainless Steel mesh 
• Water resistant  
• Re-usable / washable filter, does not require oil 

FORGED BILLET ALUMINUM AIR FILTER HOUSINGS:

• CNC machined from a single piece of forged billet aluminum  
• Features an inverted face that acts like a velocity stack by pulling in air into the top of the performance air filter 
• CNC machined style features run from the face of the intake to the backing plate for eye-catching style at every angle  

BACKING PLATE ASSEMBLY (FITMENT SPECIFIC)

08-16 FLT / 16-17 SOFTAIL & FXDLS (FBW)

Backing Plate: 18-200-1B  

Backing Plate Spacers: 18-476-3B (2)

Breather Bolts: 18-472-3 (2) 

O-Rings (6 pack): H-024-6

Throttle Body Gasket: 18-510-2

Throttle Body Hardware, 1/4-20 x 3/4: H-656Z (3) 

Shooter Tubes (2 pack): BT-002 

00-17 TWIN CAM (EXC. FBW)

Backing Plate: 18-201-1B  

Backing Plate Spacers: 18-472-2B (2)

Breather Bolts: 18-472-3 (2) 

O-Rings (6 pack): H-024-6

Throttle Body Gasket: 18-500-5

Throttle Body Hardware, 1/4-20 x 3/4: H-656Z (3) 

Shooter Tubes (2 pack): BT-002 

 91-UP XL SPORTSTER

Backing Plate: 18-202-1B  

Backing Plate Spacers: 18-202-2B (2)

Breather Bolts: 18-202-3 (2) 

O-Rings (6 pack): H-024-6

Throttle Body Gasket: 18-500-5 (2) 

Throttle Body Hardware, 1/4-20 x 3/4: H-656Z (3) 

Shooter Tubes (2 pack): BT-002 

17-UP M8 MODELS

Backing Plate: 18-203-1B  (No Spacers Needed) 

Breather Bolts: 18-457-4Z (2) 

O-Rings (4 pack): H-024-4

Throttle Body Gasket: 18-457-3

Throttle Body Hardware, 1/4-20 x 1: H-658Z (3) 

Shooter Tubes (2 pack): BT-001 

OIL CATCH ASSEMBLY 

Oil Catch / Reservoir: 18-392-3

Oil Catch Gasket: 18-392-4

Oil Catch Hardware, 8-32 x 3/4: H-619S (2) 

15-SPOKE AIR CLEANER COVER

15-Spoke Outer Cover, Black: 18-216-1B

Outer Cover Hardware, 10-24 x 5/8: H-627S (6) 

INVERTED AIR FILTER: 18-938

FILTER LOGO BADGE: 18-920-2B

99-17 TWIN CAM (EXCEPT: FBW) 

• 2001-2017 Twin Cam Delphi EFI (Fuel Injected)
• 1999-2006 Twin Cam CV Carb
• *NOTE: Will not fit Fly-By-Wire Models: 08-17 FLT Touring  / 16-17 Softail / 16-17 Dyna FXDLS & 99-01 F.I. FLT 

 08-16 TOURING / 16-17 SOFTAIL  (FBW)

• 2008-2016 FLT Touring / Bagger - FLHT / FLHR / FLHX / FLTR / H-D FL Trike 
• 2016-2017 Softails 
• 2016-2017 Dyna FXDLS 
• 2014-2015 FLSTNSE / 13-14 FXSBSE / 11-12 FLSTSE
• *NOTE: Twin Cam models equipped w/ FBW (Fly-by-Wire or Throttle-by-Wire) 

 91-UP XL SPORTSTER 

• 1991-up Sportster 883 / 1200  with CV Carb or Delphi EFI 

 17-2023 M8 MODELS (EXCEPT: 2023 FLHXSE & FLTRXSE)  

• 2017-2023 FLT Touring / Bagger - FLHT / FLHR / FLHX / FLTR 
• 2018-up Softail Models 

23-26 G2 M8 Touring, 25-26 Softails Models

Touring Models

2026 FLHXLSE CVO Street Glide Limited

2026 FLHXL Street Glide Limited

2026 FLTRXL Road Glide Limited

2026 FLHXSTSE CVO Street Glide ST

2026 FLTRXP Police Road Glide

2024-2026 FLHX Street Glide

2024-2026 FLTRX Road Glide

2023-2026 FLHXSE CVO Street Glide

2024-2026 FLTRXSTSE CVO Road Glide ST

2025 FLHXU Street Glide Ultra

2023-2025 FLTRXSE CVO Road Glide

SOFTAILS Models

2025-2026 FXLRS Low Rider S

2025-2026 FXLRST Low Rider ST

2025-2026 FLFB Fat Boy

2025 FLSTFI Fat Boy Gray Ghost

2025-2026 FLHC Heritage Classic

2025-2026 FXBB Street Bob

2025-2026 FXBR Breakout

TRIKES

2026 FLHLTSE CVO Steet Glide 3 Limited

2026 FLTRT Road Glide 3

2026 FLHLT Steet Glide 3 Limited

 22-UP NIGHTSTER SPORTSTER 

• 2022-up RH975 models 

FITMENT DISCLAIMER

Fitment information is provided as a general reference only and is not guaranteed for any motorcycle, whether stock or modified. Compatibility may vary by year, model, and individual configuration.

Customers are responsible for verifying fitment prior to purchase. House of Harley-Davidson assumes no liability for purchases made based on incorrect or unverified fitment information.

Please TEXT 414-282-2211 with any questions before ordering, or use the chat below.