The kit is called "RDO" because it transform your standard model Glock into a MOS model.
 
The raised rear sight is integrated on the plate, created with an RMSc footprint, which has a function of Co-Witness together with the front sight.
 
The kit consists of 3 pieces:
Front Sight 
Plate with Rear Sight (Co-Witness with front sight)
Attachment plate
 
The plate with rear sight and front sight are made in Aluminium, while the attachment plate was created in steel. On this system you can add the 3 Moa Micro Guardian series Dot (as shown in the photo).