AEM 21-205BF Brute Force DryFlow 4 in Conical Air Filter 6 in Base x 5.25 in H

Vehicle Fitment

• Universal - fits any cold air intake, short ram intake, or intake tube with a 4.000 in (102mm) outside diameter pipe end
• Designed for off-road vehicles, race cars, trucks, SUVs, and any build operating in dusty, harsh, or demanding environments requiring heavy-duty filter media durability and high dirt-holding capacity
• Compatible with carbureted and fuel-injected engines across gasoline, diesel, and alternative fuel applications
• Some adaptation may be required depending on installation - confirm pipe OD matches the 4.000 in flange ID before ordering

Fitment Notes

• Off-Road / Race Use Only - NOT CARB Compliant. The AEM Brute Force DryFlow filter is not legal for installation or use on emissions-controlled vehicles registered in California or other states that have adopted CARB standards. It is intended for off-road, competition, and racing applications only.
• The 21-205BF is a clamp-on universal conical filter, not a vehicle-specific drop-in panel filter. It requires a 4.000 in (102mm) OD intake tube. The flexible rubber flange absorbs vibration and provides a secure, rattle-free clamp-on installation. Secure with a standard hose clamp (not included).
• At 5.25 inches tall, the 21-205BF is the compact Brute Force 4-inch variant - suited to builds with limited under-hood height clearance where the taller 9-inch 21-2049BF (3.5-inch flange) or other tall-body filters cannot fit. Confirm available clearance before installation.
• For the 4-inch standard DryFlow street equivalent (non-Brute Force), see the 21-2057DK (tapered, 5.75-in base / 7-in height) or 21-2058DK (cylindrical, 6-in base / 7-in height). This Brute Force variant is for off-road and race use only.

Features

• Brute Force Heavy-Duty DryFlow Media - Oil-Free Synthetic for Off-Road and Racing: The 21-205BF uses AEM's Brute Force-specific synthetic filter media engineered for tough off-road and racing applications - tougher and more durable than standard DryFlow media, maintaining its structure and filtration performance under heavy dust loading, physical abuse, and repeated cleanings in demanding environments.
• Aluminum Mesh Internal Cage - High-Flow Structure: The internal cage uses aluminum meshing that straightens and smooths incoming airflow to enhance performance while maintaining the structural integrity of the filter element under engine vacuum and high-airflow conditions - preventing collapse of the filter media inward.
• Flexible Rubber Flange - Vibration Absorbing and Secure: The bendable rubber flange absorbs engine vibration and drivetrain movement, reducing stress on the intake tube connection and helping maintain a consistent, rattle-free seal over the full service life of the filter - a key durability feature for off-road vehicles operating on rough terrain.
• Compact 5.25-Inch Height - Maximum Durability in Tight Spaces: The 5.25-inch body height makes the 21-205BF the compact Brute Force option for 4-inch intake builds where taller filter bodies cannot fit - delivering Brute Force durability and media performance in a footprint that works in more restricted engine bays and intake configurations.
• Retains Shape Under Severe Abuse: The Brute Force media and aluminum mesh cage combination ensures the filter maintains its shape, seal, and performance after impacts, debris contact, and the physical stresses of off-road use under conditions that would deform conventional performance filters.
• Outstanding Filtration Efficiency and Dirt-Holding Capacity: Engineered for higher dirt-holding capacity than standard performance filters - maintaining effective filtration longer between cleanings in the heavy particulate loading typical of off-road, desert, and construction environments.
• Oil-Free - Easy to Clean: No filter oil required. Wash with AEM filter cleaner (PN 1-1000), rinse with water, air dry, and reinstall.
• Tapered Conical Profile: Tapers from a 6-inch base OD to a 5.125-inch top OD, maximizing filter media area within the compact 5.25-inch height profile.

Specifications

• Part Number: 21-205BF
• Brand: AEM Induction Systems
• Product Line: Brute Force DryFlow
• Product Type: Brute Force DryFlow Universal Clamp-On Conical Air Filter
• Color: White
• Filter Shape: Round conical (tapered)
• Filter Media: Brute Force Heavy-Duty Non-Woven Synthetic (DryFlow - oil-free)
• Internal Cage: Aluminum meshing
• Flange Type: Flexible rubber (vibration-absorbing)
• Flange Inside Diameter: 4.000 in (102mm) - fits 4-inch OD intake pipe
• Flange Angle: 0 degrees (centered, straight)
• Outside Diameter (Base): 6.000 in (152mm)
• Outside Diameter (Top): 5.125 in (130mm)
• Height: 5.250 in (133mm)
• Top Style: Closed cap
• Oiling Required: No
• Washable / Reusable: Yes
• CARB Compliance: Not CARB compliant - off-road / race use only
• Fitment: Universal
• Warranty: 1 Year Limited
• Quantity: 1 (sold individually)

Included Components

• 1x AEM Brute Force DryFlow Universal Clamp-On Conical Air Filter (21-205BF) - White
• Note: Intake pipe, hose clamp, and heat shield sold separately

Product Description

The AEM 21-205BF is a compact Brute Force DryFlow universal clamp-on conical air filter in white for 4-inch intake tubing - a 6-inch base, 5.25-inch tall tapered cone designed for off-road, racing, and performance builds that need heavy-duty filter durability in a more compact body than AEM's taller Brute Force variants. It is part of AEM's Brute Force line: a heavier-duty filter family engineered specifically for harsh, dusty off-road and competition environments where standard performance filters are not durable enough.

The aluminum mesh internal cage straightens and smooths incoming airflow while preventing filter collapse under high vacuum, and the flexible rubber flange absorbs engine and drivetrain vibration for a secure, rattle-free seal on the intake pipe. AEM's Brute Force-specific synthetic media provides outstanding dirt-holding capacity and maintains its shape under the physical stresses of off-road use. Oil-free - no oiling required. Wash with AEM filter cleaner and reinstall.

This filter is NOT CARB compliant and is intended for off-road and competition use only - not legal for street-registered vehicles in California or other CARB-adopting states. Fits any 4.000 in (102mm) OD intake tube. Universal fitment. 1-year limited warranty.