Index size on a table

It is often a requirement to understand the size of indexes on a table.
Here is a script shared by one of my friend at my workspace... looks very useful!!!

DECLARE @OBJECT_NAME  VARCHAR(255) = 'trn_defect_tracking_history';
DECLARE @temp         TABLE
        (
            indexID BIGINT,
            objectId BIGINT,
            index_name NVARCHAR(MAX),
            used_page_count BIGINT,
            pages BIGINT
        )
--Insert into temp table
INSERT INTO @temp
SELECT P.index_id,
       P.OBJECT_ID,
       I.name,
       SUM(used_page_count),
       SUM(
           CASE 
                WHEN (p.index_id < 2) THEN (
                         in_row_data_page_count + lob_used_page_count + 
                         row_overflow_used_page_count
                     )
                ELSE lob_used_page_count + row_overflow_used_page_count
           END
       )
FROM   sys.dm_db_partition_stats P
       INNER JOIN sys.indexes I
            ON  I.index_id = P.index_id
            AND I.OBJECT_ID = P.OBJECT_ID
WHERE  p.OBJECT_ID = OBJECT_ID(@OBJECT_NAME)
GROUP BY
       P.index_id,
       I.Name,
       P.OBJECT_ID;
SELECT index_name INDEX_NAME,
       LTRIM(
           STR(
               (
                   CASE 
                        WHEN used_page_count > pages THEN (used_page_count - pages)
                        ELSE 0
                   END
               ) * 8,
               15,
               0
           ) + ' KB'
       ) INDEX_SIZE
FROM   @temp T
GO