The RM21-308 is a 19-inch 2U server rack from Silverstone. Its robust steel construction provides space for numerous internal and external storage devices. Motherboards up to Micro-ATX format can be mounted. There are four low-profile slots for expansion cards. Three 80mm fans are pre-installed for cooling hardware and media.

The Silverstone RM21-308 is a 2U server chassis with a black front. In addition to large perforations for better air circulation, it also features several status LEDs, a USB 2.0 and a USB 3.0 port, as well as a power and reset button. Two handles on the front make it easier to pull the chassis out of the server rack using the optionally available telescopic rails.