Cooler Master MasterBox MB400L

mATX, Mini-ITX
Ratings
Delivered between 14.1.2026 and 21.1.2026
More than 10 pieces in stock at supplier
free shipping

Product details

Every element of the MasterBox MB400L has been designed with an elegant palette. With a brushed finish, subtle color tone, and the minimalist Cooler Master hexagon, this micro-ATX PC case enhances both gaming setups and workspaces while accommodating the latest hardware. The high style complements the high upgradability with front, top, and rear ventilation, providing additional mounting options for future cooling component upgrades. When an optional RGB or ARGB fan is installed behind the front panel, the Cooler Master hexagon on the front panel lights up. In total, up to 6 fans can be mounted simultaneously to ensure that even the most demanding cases stay cool under heavy load.

Key specifications

PC case design
Mini Tower
PC case features
Side windows
Max. length graphics card
344 mm
Max. height CPU cooler
167 mm
Number of 3.5" drive slots (internal)
2 x
Item number
15666151

General information

Manufacturer
Cooler Master
Category
PC case
Manufacturer no.
MCB-B400L-KN5N-S00
Release date
15.4.2021

Colour

Colour
Black
Exact colour description
Black

Material

Material group
Metal, Plastic
Material
Iron, Plastic

PC case properties

PC case design
Mini Tower
Form factor
Micro ATX (mATX), Mini-ITX
"Number of 5.25"" drive slots"
1 x
Number of 3.5" drive slots (external)
2 x
Number of 3.5" drive slots (internal)
2 x
"Number of 2.5""/3.5"" combination slots"
2 x
"Number of 2.5"" drive slots"
2 x
Number of expansion card slots
4 x
Max. length graphics card
344 mm
Max. height CPU cooler
167 mm
PC case features
Side windows

Cooling properties

Number of fan slots
6 x
Cooling properties
Water cooling possible

Front side

Fans included
1x 120mm
Fan mount locations
2x 120mm

Rear side

Fans included
1x 120mm
Fan mount locations
1x 120mm

Top side

Fans included
1x 120mm
Fan mount locations
2x 120mm
Radiator mount locations
1x max. 120mm

HDD Cage

Fans included
1x 120mm
Fan mount locations
1x 120mm
Radiator mount locations
1x max. 120mm

Origin

Country of origin
China

Voluntary climate contribution

CO₂-Emission
Climate contribution

Scope of delivery

Scope of delivery
PC

Product dimensions

Height
41 cm
Length
41.10 cm
Width
21 cm
Weight
5.20 kg

Package dimensions

Length
48 cm
Width
48.50 cm
Height
28.50 cm
Weight
5.83 kg

30-day right of return
24 Months Warranty (Bring-in)

Compare products

Goes with

Reviews & Ratings

Warranty score

How often does a product of this brand in the «PC case» category have a defect within the first 24 months?

Source: Digitec Galaxus
  • 17.Hyte
    0.6 %
  • 17.Intertech
    0.6 %
  • 21.Cooler Master
    0.7 %
  • 21.Jonsbo
    0.7 %
  • 23.Sharkoon
    0.8 %

Warranty case duration

How many working days on average does it take to process a warranty claim from when it arrives at the service centre until it’s back with the customer?

Source: Digitec Galaxus
  • 1.NZXT
    0 days
  • 4.be quiet!
    1 day
  • 4.Cooler Master
    1 day
  • 4.Lian-Li
    1 day
  • 4.Montech
    1 day

Return rate

How often is a product of this brand in the «PC case» category returned?

Source: Digitec Galaxus
  • 18.Endorfy
    4.5 %
  • 21.ASUS
    4.7 %
  • 22.Cooler Master
    4.8 %
  • 23.Darkflash Tech
    4.9 %
  • 24.Jonsbo
    5.5 %
Source: Digitec Galaxus