Creating a dropdown list that coresponds to different cells

I would like to know how to create a drop down list for a specified set of values, I want these values to correspond to a different value
for example

Rough Concrete corresponds to 0.8

so when i select the name such as rough concrete the value 0.8 appears in a cell below the drop down menu, however i would like all the values to appear in the same cell

Any response would help me greatly
Thankyou for your time and effort