Delcare variable for Multiple values paramter in SP ???

Hi i get an error when I show multiple values in the parameterDo I declare the variable differently in the SP?...@Code varchar(10) ,@Days varchar(10) ,@Begin VARCHAR(10) , @End varchar(10) , [b]@Zip varchar(1000)[/b] Zip is the only parameter to accept multiple values.. the where clause is like....where..... AND dbo.Address.Zip in (@Zip)