Physical Dimensions: Overall (with 1 T-bar): 43 1/2 x 29 7/8 x 3/8 in. (110.5 x 75.9 x 1 cm)
Overall (installation opening): 41 3/4 x 28 3/8 in. (106 x 72.1 cm)
a: 21 13/16 x 29 3/8 x 3/8 in. (55.4 x 74.6 x 1 cm)
b: 21 9/16 x 29 1/8 x 3/8 in. (54.8 x 74 x 1 cm)