SELECT
	Descript, 
	MyString, 
	p2 = UNICODE(SUBSTRING(MyString,2,1)) 
FROM (
	SELECT Descript = 'Normal Latin F', MyString = CAST(N'4F' AS NVARCHAR(2)) UNION ALL
	SELECT Descript = 'Wide Latin F', N'4Ｆ'
) d
--WHERE MyString = '4F' -- need a width-sensitive collation here
WHERE MyString = N'4Ｆ' -- need a width-sensitive collation here