Case when and parameter

I'm trying to figure out how to do a CASE WHEN for a parameter. Instead of having the I.fgroup name show up for the parameter as the drop-down, I want to be able to have a more user friendly name (ie Aluminum instead of #ALF)

Below is what I'm using for the dataset that the parameter gets it available values.

select distinct 
WHEN  I.fgroup = '#ALF' then 'Aluminum Strip'
WHEN  I.fgroup = '#CUF' then 'Copper Strip'
WHEN  I.fgroup = '#CAB' then 'Wire'
WHEN I.fgroup = '#INS' then 'Insulation'
end as 'Material'

I would recommend adding this as a description column on the table that has the fgroup. that way if a new group is added you don't have to come here to this select and add it manually and so on