5” slide rules
Unique Universal 1, made in England, c.1955
No 11 ZR Albert Nestler, made in Germany, c. 1960
J.H. Liddle & Epstein P/L, made in Sydney, c.1962
The 5” [125mm] slide rules were made to fit in the pocket, for calculations on the go! These slide rules come in their original plastic or leather cases; and the middle slide rule has its original owner’s formulae incised on the back [perhaps for cheating on tests!]
Since this image was taken, I have collected another 5” slide rule; so if this is your thing, let me know.