This is a draw bar potentiometer, model RS40D113A0000. It is manufactured by the Alps Electronics company.
Specifications are as follows:
As bar pulled out it shows numbers 1 thru 8
Unit has detents so that when pulled you can feel the changes. There are 16 detents total.
Range: From 10k ohms with the draw bar all the way out, number 8 showing down to approximately 5 ohms with the draw bar in, number 1 showing.
Item weight is .04 pounds.