1. Simple trigonometry rule.
2. This rule shares the same model number as the N901-ES Simplex Math Rule yet these two rules are different in many ways. The front scales are similar although this rule has the K scale on the front. This rule however is a simplex rule and the reverse has various tables and no scales.

Brand	Pickett
Model	N901-T Simplex
Country of Manufacture	USA
Scales Front	K, A [B, CI, C] D, DI
Scales Back	None
Number of Scales	7
Slide Rule Materials	Aluminium
Cursor Materials	Metal/Plastic with Metal Screws
Cursor Lines	1 Front
Scale Length	25 cm
Length	30.7 cm
Width	3.2 cm
Condition	Good
Documentation	None
Accessories	Vinyl Slip Case