AEM 21-2031D-HK DryFlow 3 in Red Conical Air Filter 6 in Base x 5 in H Universal

Vehicle Fitment

• Universal - fits any cold air intake, short ram intake, or intake tube with a 3.000 in (76mm) outside diameter pipe end
• Suitable as a replacement filter on existing AEM cold air intake systems using 3-inch intake tubing, or as a primary filter element on custom intake builds
• 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 3.000 in flange ID before ordering

Fitment Notes

• The 21-2031D-HK is a clamp-on universal conical filter - it is not a vehicle-specific drop-in panel filter. It requires a 3.000 in (76mm) OD intake tube or pipe end. Secure with a standard hose clamp (not included) over the 1.500 in flange length.
• Filter dimensions: 6.000 in OD base tapering to 5.125 in OD at the top, 5.000 in height. Confirm available under-hood clearance for the full filter body before installation.
• The flange is centered at 0-degree offset - the filter mounts straight onto the intake pipe with no angular offset. For angled or offset flange configurations, see other AEM DryFlow universal filter variants.
• The "HK" suffix denotes the red colorway, which is the standard street-use DryFlow color. The black equivalent is the 21-2031DK. Both filters share identical dimensions, media, and performance specifications - color is the only difference.
• For replacement filters on AEM cold air intake systems, verify this part number matches the original filter supplied with your specific AEM intake kit before ordering.

Features

• AEM DryFlow Oil-Free Synthetic Media - Up to 99% Filtration Efficiency: The 21-2031D-HK uses AEM's DryFlow non-woven synthetic filter media, delivering high airflow and up to 99% contaminant capture efficiency without requiring filter oil. Unlike oiled cotton-gauze performance filters, DryFlow eliminates the risk of MAF sensor contamination from oil overspray, and the synthetic media does not degrade from repeated cleaning cycles the way cotton gauze can.
• Tapered Conical Profile - More Filter Area in Less Height: The cone shape tapers from a 6-inch base OD to a 5.125-inch top OD across a 5-inch height, providing more filter surface area than a straight cylindrical filter of equivalent height while maintaining a compact profile that fits well in tighter engine bays and around various under-hood obstacles.
• Reinforced Internal Cage - Lighter and Stronger Than Mesh: The internal support structure uses a reinforced cage design that is lighter and structurally stronger than conventional wire mesh cages, resisting collapse under engine vacuum and high-airflow conditions while reducing overall filter weight.
• Urethane Body - Won't Shrink or Crack: The filter body is constructed from urethane rather than plastisol-based compounds, maintaining its shape and sealing properties across the full temperature range of automotive use - it will not shrink over time or crack from heat cycling.
• Integrated Velocity Stack in Flange Neck: The 3-inch flange incorporates an integrated velocity stack profile in the inlet neck, improving structural rigidity and smoothing airflow entry into the filter body for improved overall filter flow capacity.
• Closed Rubber Top Cap - Filter Top for Higher Airflow: The closed rubber top cap seals the top of the filter, directing all incoming air through the full conical media surface area rather than short-circuiting through an open top. AEM describes this as a "filter top for higher air flow capability."
• Flows Well Even When Dirty: AEM's non-woven synthetic media is engineered to shed trapped dirt particles under engine vibration, maintaining consistent airflow as the filter accumulates contaminants - performing nearly as well dirty as it does clean, unlike cotton-gauze filters that progressively restrict flow as dirt builds up.
• Washable and Reusable - Lifetime Filter: AEM DryFlow universal filters are washable with AEM filter cleaner (PN 1-1000), rinsed with water, air dried, and reinstalled - no oiling required. Designed to last for the life of the vehicle or intake system.
• Will Not Void Vehicle Warranty: The 21-2031D-HK will not void the OEM manufacturer's vehicle warranty when used as directed.
• Made in the USA: Manufactured by AEM Induction Systems to precision quality standards.

Specifications

• Part Number: 21-2031D-HK
• Brand: AEM Induction Systems
• Product Type: DryFlow Universal Clamp-On Conical Air Filter
• Color: Red
• Filter Shape: Round conical (tapered)
• Filter Material: Non-Woven Synthetic (DryFlow - oil-free)
• Flange Inside Diameter: 3.000 in (76mm) - fits 3-inch OD intake pipe
• Flange Length: 1.500 in
• Flange Angle: 0 degrees (centered, straight)
• Flange Type: Centered (1 flange)
• Outside Diameter (Base): 6.000 in (152mm)
• Outside Diameter (Top): 5.125 in (130mm)
• Height: 5.000 in (127mm)
• Top Style: Rubber cap (closed - "filter top")
• Frame Design: Flexible reinforced internal cage
• Oiling Required: No
• Washable / Reusable: Yes
• Filtration Efficiency: Up to 99%
• Country of Manufacture: USA
• UPC: 024844298546
• Warranty: Lifetime Limited
• Quantity: 1 (sold individually)

Included Components

• 1x AEM DryFlow Universal Clamp-On Conical Air Filter (21-2031D-HK) - Red
• Note: Intake pipe, hose clamp, and heat shield sold separately

Product Description

The AEM 21-2031D-HK is a universal DryFlow clamp-on conical air filter in red for 3-inch intake tubing - a tapered cone measuring 6 inches at the base, 5.125 inches at the top, and 5 inches tall, with a 3-inch centered inlet flange. It is designed for use on custom intake builds, cold air intake systems, or as a direct replacement filter element on existing AEM intakes using 3-inch pipe. The red "HK" colorway is functionally identical to the black "DK" variant - the 21-2031DK - with dimensions and performance specifications shared between both.

AEM's DryFlow oil-free synthetic media delivers up to 99% filtration efficiency without requiring filter oil, eliminating MAF sensor contamination risk and simplifying maintenance to a wash-and-reinstall cycle. The tapered conical profile delivers more filter surface area in a compact 5-inch height than an equivalent straight cylindrical design, and AEM's non-woven media is engineered to shed dirt under engine vibration - maintaining consistent airflow performance even as the filter loads up. The reinforced internal cage, urethane body, and integrated velocity stack in the flange neck ensure structural integrity across the filter's service life.

Fits any 3.000 in (76mm) OD intake tube. Some adaptation may be required depending on the installation. Secured with a standard hose clamp over the 1.500 in flange. Washable and reusable for the life of the vehicle. Made in the USA. Backed by AEM's Lifetime Limited Warranty.