The ASUS A21 PLUS microATX case is designed for minimalist mainstream DIY PC builders, offering support for hidden-connector motherboards, 360 mm radiators, and 380 mm graphics cards. It features four pre-installed ARGB fans for exceptional cooling and a 40% porous front-panel mesh for optimized airflow, dust filtering, and RGB visibility. The case includes a 33 mm wide compartment behind the motherboard for clean cable management. It supports ATX PSUs, has 5 expansion slots, 1 x 2.5" bay, and 1 x 3.5" bay. Maximum PSU length is 21 cm, maximum graphics card length is 38 cm, and maximum CPU cooler height is 16.5 cm. The case supports 120 mm, 140 mm, 240 mm, 280 mm, and 360 mm radiators in the front and top, and 120 mm in the rear. It has space for up to 3 top fans (120/140 mm), 1 rear fan (120 mm), and up to 3 front fans (120/140 mm). It comes with a colour-coordinated white internal I/O cable.