Concise circular slide rule - model 270N with an Instruction Manual for very similar Concise circular rule. A slide rule used by students, engineers, ... up to the 1960s.

Works perfectly, in excellent condition. No case.

As in photos- scales A, D, C, CI, B, K and L on the front and DI, D, S, T and ST on the reverse. Multiplication, powers, conversions and much much more ... plenty of additional info on using, beyond what is in the Instruction Manual, on Google etc..

The chance to revisit times before the electronic calculator arrived - as used in the classroom and at work. Something different for a present for a parent, mathematics enthusiast and ideal for display.