The Pentax 645Z IR is a special version of the Pentax 645Z
with the infrared filter in front of the sensor removed.
The 645Z IR can be used for normal photography if you put an IR blocking filter in front of the lens. Apart from the removal of the IR filter, the camera itself is identical to the 645Z.
Manual focus can conveniently be done using live view whereas the viewfinder would be inaccurate for focusing IR images due to the much different wavelength of IR compared to visible light. In this sense the 645Z is more suitable for IR photography than was the 645D IR.
Ricoh Imaging Co. announced this camera in November of 2015. This camera will not be made available to general customers for personal use.