21.40

4'10 x 17 1/2 x 2 1/16 18.9L 4'6 x 17 1/4 x 2 16.8L 5'0 x 17 3/4 x 2 1/8 20.4L 5'2 x 18 x 2 1/8 21.4L +1

4'10" 17 3/4" 1 3/4" = 15.7L 5'0" 17 7/8" 1 7/8" = 17.3L 5'1" 18" 2" = 18.5L 5'2" 18" 2 1/16" = 19.5L +7