The Interior kit is includes a lot of steps and refers to what parts/build steps from the main tank kit you need to do to build the whole tank correctly which is a great help and very easy to follow. There are also several parts that will not be used as they are from the other version of the King Tiger with the Henschel turret. Also a very good idea is the amount of painting instruction details given at each of the build stages.
Step 1 through 6 - builds parts of the lower hull and suspension real no issues. I would suggest that the part numbers M2 and M6 (stage 3 and 4) at Stage 1 before the cross supports are installed to easy installation. I also found it would be easy to install P50 incorrectly. The part M8 was also a tight fit. The parts Q10 and Q1 need to carefully be installed.