The Crew Capsule Dockable is small stage similar to a Crew Capsule, but is dockable.
During rocket assembly, 1 Battery, 1 Oxygen Tank and 1 Carbon Dioxide Scrubber are pre-loaded. These three Cargo items may be removed/replaced during assembly, or in space after launch. Additionally, it's equipped with a parachute which can be deployed during the latter stage of capsule Re-entry into a planet's atmosphere.
The capsule is used in Missions 14 "Lunar Orbit" and Mission 16 "Moon Landing", attached to the Apollo Service Module. It's based off of the Apollo capsule, which was used from 1966 to 1975 throughout the Apollo and Apollo-Soyuz programs.
It is reentry capable and its thrusters are capable of propelling it backwards, just like the undockable version.