Unified (Block II) Command Module Hatch
Here is a diagram of the "Unified" (Block II) command module hatch. It is referred to as a "unified" hatch because it incorporates both the outer heat shield hatch and inner crew compartment pressure hatch in a single hatch. This hatch was initially flown on Apollo 6.
Additional information on the Block II hatch, with an emphasis on the changes from the Block I hatch, can be found in The Apollo Command Module Side Access Hatch System. This includes photos of the hatch installed in the command module.