Full Details

Name and Model Number Aristo 940 Stahlbeton
Country of Origin Germany
Date of Manufacture 1973
Front Scales Fe, me, Me A, b B, me BI, k, CI,(k,b) C, ke, h
Back Scales Charts and Tables
Scale Length 25 cm + 2.2 cm extension
Type of Rule Slide Rule
Construction Plastic
Area of Use Concrete
Rarity RR
Donor Collection of Rod Lovett
Match Number 11

RR = Rare -- 1 of 25 collectors has one; it may take a year to find an example in the marketplace.   
RRR = Very rare -- only very few known to collectors; may take several years before one comes up for sale.   
RRRR = Extremely rare -- a museum piece; unlikely that an example will ever come up for sale.