The first commercially flown CubeSat deloyer used on the International Space Station. Each deployer is capable of deploying 6Us of CubeSats. Typically a cluster of eight deployers are used per mission.
The Cygnus capability to boost itself higher after finishing its primary ISS mission lead to the development of the External CubeSat Deployer, or ECSD to provide a higher orbit opportunity for CubeSats. This system is capable of deploying 36Us of CubeSats.
Sling Shot is a unique deployment system that was designed and developed for SEOPS LLC. This system can be loaded with up to 9 deployers and the system is capable of deploying 54U of CubeSats. Slingshot also takes advantage of the Cygnus altitude boost capability to give customers a desirable higher orbit.
The NanoRacks Kaber deployer is an express class (82kg max) satellite deployer utilizing a Quad-M designed and built separation mechanism.