Convert your Pentax 6x7 200mm f/4 to 400mm f/8 or your 135 macro to 270mm.  This Komura Telemore 95 2x extender can do it for on the Pentax 6x7 or 67.  It is in the original case and in Mint Condition, except that there is dust inside both the front and rear lenses.  Just remove a few screws to easily clean these elements.  Comes with front cap only.  Rear cap is missing.