LIAN LI has introduced the B4-mATX, a 21.3-liter small form factor chassis developed in collaboration with DAN Cases. Despite its compact footprint, the B4-mATX supports mATX motherboards, graphics cards up to 358mm in length, and both ATX and SFX power supplies. The chassis can be used in either a horizontal desktop orientation or a vertical tower configuration to reduce desk space usage. Available with mesh or real wood front panels in black or white, the B4-mATX is designed to suit a wide range of PC builds and setups.



One Chassis, Two Orientations
The LIAN LI B4-mATX is designed to operate in either a horizontal desktop layout or a vertical tower configuration, with the latter reducing desk space usage by up to 30%. A rotatable AC inlet accommodates both orientations, allowing for easier cable management and excess cable storage when positioned vertically. In addition, a swiveling cable bracket beneath the PCIe slots helps keep rear I/O and power cables neatly aligned, supporting connectors up to 52mm in height. Users can choose between a perforated mesh front panel for improved airflow or a real wood finish in walnut or beech, with both options offered in black and white colourways.

Flexible Design — ATX or SFX, Air or Liquid
The LIAN LI B4-mATX comes equipped with two pre-installed 120×120×15mm slim non-RGB exhaust fans mounted on a removable bracket. The front fan can be repositioned as an intake to better support air-cooled systems. The chassis supports both SFX and ATX power supplies via dedicated mounting brackets, providing flexibility for different builds. When using an SFX power supply, users can install side-mounted radiators up to 360mm with a maximum thickness of 52mm, while systems using a 140mm ATX power supply support radiators up to 240mm. A reversible rear fan bracket can also be adjusted to optimise airflow for tower air coolers or create additional clearance for side-mounted liquid cooling solutions.

Compact Footprint, Full-Size Hardware
Despite its compact 21.3-litre volume, the LIAN LI B4-mATX supports graphics cards up to 358mm in length across four expansion slots and CPU air coolers up to 162mm tall, or up to 168mm with the side fan bracket removed. The chassis also includes a pre-installed adjustable anti-sag bracket to provide additional support for larger graphics cards without obstructing GPU cooling fans. Storage options include support for one 3.5-inch hard drive or 2.5-inch SSD at the bottom, plus an additional 2.5-inch SSD mounting location at the front.

Optional B4-mATX Vertical AeroDeck
LIAN LI also offers the optional B4-mATX Vertical AeroDeck accessory for systems configured in the vertical orientation. The AeroDeck improves GPU airflow by adding support for up to three 120mm fans or two 140mm fans and features tempered glass side panels to showcase the installed cooling setup. A magnetic PVC dust filter is also included. Matching the aesthetics of the B4-mATX Wood variant, the AeroDeck is available with walnut or beech wood accents and comes in both black and white finishes.

Pricing and Availability
The LIAN LI B4-mATX and optional Vertical AeroDeck accessory will be available starting June 26, 2026. Pricing is as follows:
• B4-mATX Mesh Black – $69.99 / €69.99
• B4-mATX Mesh White – $74.99 / €74.99
• B4-mATX Wood Black – $84.99 / €84.99
• B4-mATX Wood White – $89.99 / €89.99
• B4-mATX Vertical AeroDeck (Black or White) – $29.99 / €29.99