2x Sun Hemmi P40RK + 40RK Slide rule case Japan

This is an interesting combination of 2 identical type rules by the same maker, but with a lot of variation in building materials, age, case, number etc. One is the earlier bamboo type 40RK in cardboard case, the other the all plastic version R 40PK in plastic case everything made in Japan by Sun Hemmi (where the last one could have been specially made for the Dutch market).  Both slide rules and cases are complete and in great condition with minimal signs of use and age. Nice addition to any collection or just to play “find the differences” game. They measures ca. 28,5 cm or 11 1/4 inches. Check out the attached video on how to operate a vintage slide rule!