Physical Dimensions: Overall (with 1 T-bar): 43 1/2 x 29 5/16 x 3/8 in. (110.5 x 74.5 x 1 cm)
Overall (installation opening): 41 3/4 x 28 3/8 in. (106 x 72.1 cm)
a: 21 7/8 x 29 1/4 x 3/8 in. (55.6 x 74.3 x 1 cm)
b: 21 3/4 x 29 1/4 x 3/8 in. (55.2 x 74.3 x 1 cm)