Full Details

Name and Model Number Aristo 929 Technica
Country of Origin Germany
Date of Manufacture ~1955
Front Scales K, DF [CF, CIF, CI, C] D, L
Back Scales cm / P, A [B, T, ST, S] D, DI /ins
Scale Length 25.0 cm + 2.5 cm extension
Type of Rule Slide Rule
Construction Plastic
Area of Use Generic
Rarity RR
Donor Collection of Rod Lovett
Match Number 13

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.