The Jonsbo U4 Black Compact ATX Tower Computer Case from SeaSonic Electronics is designed to be used with ATX, Micro-ATX, and Mini-ITX motherboards. It supports VGA cards up to 12.2" long and CPU coolers up to 6.7" high. ATX power supplies up to 9.8" can be installed and this case has seven PCI expansion slots.

Hard disks can be mounted using rubber suspension for a silent operation of the system. Either two 2.5" and three 3.5", or two 3.5" and two 2.5" HDDs or SSDs can be mounted. The U4 comes with a quiet 120mm fan preinstalled at the rear panel. The cooling system can be optimized by further fans, with mounting points for two 120mm fans behind the front and with a 120mm fan at the bottom of the case. This case features vibration-decoupled feet.