The caddy is designed to fit the optical drive bay of a HP Proliant Microserver Gen8 and will latch into the locking mechanism. It is short enough for the original slot cover to fit.The tray accomodates a 2.5" SSD (or HDD). Some information about the evolution of this design can be found here (sorry - German only): http://cepp-techblog.blogspot.com/2016/01/ssd-caddy-fur-dvd-bay.html