Lian Li B4 mATX Mesh Black - G99.B4X.00

Lian Li B4 mATX Mesh Black - G99.B4X.00

The Lian Li B4-mATX is a compact 21.3-litre small form factor case co-developed with DAN Cases, supporting Micro-ATX and Mini-ITX motherboards in a remarkably small footprint. This black model features a high-airflow mesh front panel and can be positioned horizontally or vertically, cutting the footprint by around 30 per cent in vertical mode. Despite its size it takes graphics cards up to 358mm, CPU coolers up to 168mm and radiators up to 360mm, with two 120mm slim fans pre-installed.

Compact Without Compromise

At just 21.3 litres the B4-mATX packs full Micro-ATX capability into a genuinely compact chassis, making it an excellent choice for a powerful small form factor build. It accommodates 4-slot graphics cards up to 358mm long, CPU air coolers up to 168mm tall, and supports both ATX power supplies up to 140mm and compact SFX units. That combination means you rarely have to compromise on components to fit the smaller footprint.

Cooling and Airflow

Cooling is a highlight, with support for up to nine fans and radiators up to 360mm when paired with an SFX power supply, or 240mm with a full-size ATX unit. Two 120mm slim fans come pre-installed on a removable bracket, and the heavily meshed panels to keep airflow moving through the chassis. Reviewers have consistently praised the B4's thermal performance for a case of this size.

Flexible Placement

The dual-orientation design lets you stand the case vertically to save desk space or lay it horizontally beneath a monitor, and Lian Li's optional Vertical AeroDeck accessory is available to complement the vertical layout. Finished in black with a mesh front, it offers a clean, understated look that suits a living-room or desktop setting. Modular internal brackets make building and later upgrades straightforward.

Specifications

General

Case