MSD-221 Missile Rack

The Behring MSD-221 "Marsden" Missile Rack is a size 2 missile rack that is able to carry two size 1 missiles.

In-game description
"Behring’s MSD-221 'Marsden' is a complete ordnance storage and deployment system that can be mounted on any compatible size 2 hardpoint for the reliable and effective launch of two S1 missiles."