Drop down list and formula

I have created a drop down list as follows

Whiteboard 16mm
Colourboard 16mm
Colourboard 18mm
Veneer 18mm
Veneer 19mm
Veneer laid up 40mm
Painted 16mm
Painted 18mm.

When I select one of these items I need CELL A1 to return just the thickness.

EG: I hit dropdown list and select Whiteboard, CELL A1 then displays 16mm.
Or I select Veneer laid up and it displays 40mm.
I would imagine this formula would be quite long as I would have these 8 items in it.

Can you show me an example of what to do in simple format to produce this.

Thanks Guys
Roger.