Upper Arch RTP_Base:
All RTP_Bases have common features as shown in the above picture and come in three sizes (small = blue, medium = green, large = orange). All bases are made from a translucent plastic so they can be held up to a light to determine the position of the die pin when sawing dies.
The die pin holes are precision tapered to receive a Removable Tapered Pin (hence the RTP designation). The index pins prevent the die from rotating or twisting and are strategically located to prevent putting a die into the wrong location. (However, this does not prevent you from putting a die into the same location on the wrong base.)
All standard RTP_Bases have engravings between the first and second molars to designate Upper or Lower and Left or Right.