backing strip

13 LETTERS · STARTS WITH B

backing strip is a valid 13-letter word worth 23 points in Scrabble and 28 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS

B3A1C3K5I1N1G2S1T1R1I1P3

3 + 1 + 3 + 5 + 1 + 1 + 2 + 0 + 1 + 1 + 1 + 1 + 3 =23 PTS

DOUBLE WORD → 46TRIPLE WORD → 69

MEANING

What does backing strip mean?