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Black micro-ATX tower with mesh front panel and tempered glass side panel

ASUS

ASUS A21/BLK// Micro ATX PC Case Black

SKU CH-13PC-JADJY MPN A21/BLK//

A micro-ATX chassis of steel, plastic and tempered glass with a 40% porous front mesh, room for 360 mm radiators, 380 mm graphics cards and 165 mm CPU coolers, plus a 33 mm rear cable compartment

  • TypeMicro ATX
  • ColorBlack
  • Case MaterialSteel / Plastic / Tempered Glass
  • Motherboard CompatibilityMicro ATX / Micro ATX (Back Connect) / Mini ITX
  • Dust FiltersBottom / Top
  • Internal 3.5" Drive Bays2

Options A21 (Black)

  • Clean cable management with BTF hidden-connector motherboard support
  • 33 mm rear compartment keeps wiring tucked away and tidy
  • 40 % porous front mesh balances airflow, dust filtering and RGB visibility
  • Supports 360 mm radiators, 380 mm graphics cards and 165 mm CPU coolers
  • Black internal I/O cables match your build theme

Compact Micro ATX Chassis

The ASUS A21 is a Micro ATX case built from steel, plastic and tempered glass in a black finish. It accepts Micro ATX, back-connect Micro ATX and Mini ITX motherboards. The design targets builders who want a smaller footprint without sacrificing component clearance or cooling headroom.

Mesh Airflow and Cable Management

A front mesh panel rated at 40 percent porosity balances airflow, dust filtering and RGB visibility. Dust filters sit at the bottom and top. The rear cable compartment measures 33 mm wide for tidy routing. Color-coordinated black internal I/O cables match the theme. Front I/O supplies two audio jacks and two USB 3.2 Gen 1 ports.

Cooling and Component Limits

The case fits graphics cards up to 380 mm long and CPU air coolers up to 165 mm tall. Radiator support reaches 360 mm at the front and top, plus 120 mm at the rear. Fan mounts allow three 120 mm or two 140 mm units at front and top, plus one 120 mm rear. Two 3.5-inch and one 2.5-inch drive bays are available. The power supply compartment accommodates units up to 210 mm long.

Highlights

  • Clean cable management with BTF hidden-connector motherboard support
  • 33 mm rear compartment keeps wiring tucked away and tidy
  • 40 % porous front mesh balances airflow, dust filtering and RGB visibility
  • Supports 360 mm radiators, 380 mm graphics cards and 165 mm CPU coolers
  • Black internal I/O cables match your build theme

Specifications

BrandASUS
ModelA21/BLK//
Part Number90DC00H0-B08000
TypeMicro ATX
ColorBlack
Case MaterialSteel / Plastic / Tempered Glass
Motherboard CompatibilityMicro ATX / Micro ATX (Back Connect) / Mini ITX
Dust FiltersBottom / Top
Internal 3.5" Drive Bays2
Internal 2.5" Drive Bays1
Expansion Slots5
Front Ports2 x Audio, 2 x USB 3.2 Gen 1
Fan OptionsFront: 3 x 120 mm / 2 x 140 mm
Top: 3 x 120 mm / 2 x 140 mm
Rear: 1 x 120 mm
Radiator OptionsFront:120 mm / 140 mm / 240 mm / 280 mm / 360 mm
Top: 120 mm / 140 mm / 240 mm / 280 mm / 360 mm
Rear: 120 mm
Max GPU Length380 mm
Max CPU Cooler Height165 mm
Max PSU Length210 mm
Dimensions18.3" x 8.7" x 16.9"
Weight18.52 lbs.
Shipping weight8.39 kg
Package size508 × 508 × 279 mm

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Questions about this item

What USB standard do the front ports use and what is the practical speed limit?

The front panel has two USB 3.2 Gen 1 ports, which operate at up to 5 Gbps in practice.

What motherboard form factors and clearance dimensions does the chassis accept?

It fits Micro ATX, Micro ATX Back Connect and Mini ITX boards, with 380 mm GPU length, 165 mm CPU cooler height and 210 mm PSU length limits.

How are the dust filters removed for cleaning and which step is often missed?

Bottom and top filters slide out; the top filter is often forgotten because it sits under the removable panel.

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