This high quality metal circular slide rule is of the larger variety. It measures a whooping 30 cm or 12 inches in diameter. This one is close to new in the box, probably from the 1960’s. This is the elaborate model 75T for all the basic calculations using square roots, sinus and tanges and log scales. The size gives the user extra accuracy and to enhance this even further the cursor has additional increments on the end scale. It was ment to be used, holding in one hand to turn the knob on the back to manipulate the centre scales. The cursor could be set with the other hand. There was also a special stand available to make it hover on your desk (not included). The slide rules shows minimal signs of use and age (small cracks in the grey paint on the rim only), the green color is still very vibrant. The original cardboard case is showing minimal signs of use and age as well but has 1 tear on the lid corner. Check the attached video on how to work your vintage man tool : slide rule operation instructions!
