BROAD COMPATIBILITY
Despite being a micro-ATX case, the A21 still supports up to 360 mm radiators, graphics cards up to 380 mm in length and CPU air coolers up to 165 mm in height, giving builders plenty of options to assemble their next PC.
CAPABLE COOLING
The front-panel mesh of the A21 is 40% porous to maximize the balance of airflow and RGB visibility. Users can add up to three 120 mm fans to this section of their build to solidly manage system temperatures.
AMPLE CABLE MANAGEMENT
The A21 provides a compartment behind the motherboard that is 33 mm wide to help you keep your wiring tucked away and tidy.
Source : Asus A21