Anyone know what this is for??

[Bishop]

A friend of mine found this and really wants to know what it is, now so do I. Any ideas?



Thanks
Shawn

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And I know "it's a ruler"

 

[pdentrem]

It is called a ruler. I have one just like it.)

The yellow thing I do not know. Appears to have timing marks of tenths of something on the right. What does the rest look like?
Pierre