1. This log log decimal trig rule is of a similar age and design as the Acu-Math 511 (1) in my collection.
2. I have a later version of this Acu-Math 1311 (2) which shows the changes which were made between the two examples.

Brand	ACU-MATH
Model	No. 1311 - Log Log Decimal Trig
Country of Manufacture	USA
Scales Front	LL02, LL03, DF [CF, CIF, CI, C] D, LL3, LL2
Scales Back	LL01, K, A [B, T, ST, S] D, L, LL1
Number of Scales	20
Slide Rule Materials	Metal core, plastic faces with metal end pieces on back only. Metal core looks like magnesium
Cursor Materials	Plastic
Cursor Lines	1 Front, 1 Back
Scale Length	25 cm
Length	31.7 cm
Width	3.9 cm
Condition	Good.
Documentation	None
Accessories	Leather Case Original Box