A static mixing device subassembly, said subassembly comprising: a first grid formed of a first set of spaced-apart and parallel-extending deflector blades; a second grid formed of a second set of spaced-apart and parallel-extending deflector blades that are interleaved with and cross the first set of deflector blades at a preselected angle, adjacent ones of the interleaved deflector blades (18, 20) in the first and second sets (16, 14) each having opposite ends (22, 24, 30, 32) and side edges (26, 28, 34, 36), the side edges (26, 28, 34, 36) having uncut portions that join the adjacent ones of the interleaved deflector blades (18, 20) along a transverse strip where the deflector blades (18, 20) cross and cut portions that extend from the uncut portions to the opposite ends (22, 24, 30, 32) of the deflector blades (18, 20), the deflector blades in the second grid each having a bent portion that places planar segments (20a, 20b) of the deflector blade on opposite sides of the uncut portion in offset planes; a third grid formed of a third set of spaced-apart and parallel-extending deflector blades; and a fourth grid formed of a fourth set of spaced apart and parallel-extending deflector blades that are interleaved with and cross the third set of deflector blades at a preselected angle, adjacent ones of the interleaved deflector blades in the third and fourth sets each having opposite ends and side edges, the side edges having uncut portions that join the adjacent ones of the interleaved deflector blades along a transverse strip where the deflector blades cross and cut portions that extend from the uncut portions to the opposite ends of the deflector blades, the deflector blades in the fourth grid each having a bent portion that places planar segments of the deflector blade on opposite sides of the uncut portion in offset planes, wherein one of the ends (22, 24) in at least some of the deflector blades in the first set is uncut and is interconnected with an uncut one of the ends of the deflector blades in the third set along a reverse bend that aligns the first and second grids (16, 14) of deflector blades (18, 20) with the third and fourth grids of deflector blades, characterized in that the deflector blades of the first set are planar and the deflector blades of the third set are planar. a first grid formed of a first set of spaced-apart and parallel-extending deflector blades; a second grid formed of a second set of spaced-apart and parallel-extending deflector blades that are interleaved with and cross the first set of deflector blades at a preselected angle, adjacent ones of the interleaved deflector blades (18, 20) in the first and second sets (16, 14) each having opposite ends (22, 24, 30, 32) and side edges (26, 28, 34, 36), the side edges (26, 28, 34, 36) having uncut portions that join the adjacent ones of the interleaved deflector blades (18, 20) along a transverse strip where the deflector blades (18, 20) cross and cut portions that extend from the uncut portions to the opposite ends (22, 24, 30, 32) of the deflector blades (18, 20), the deflector blades in the second grid each having a bent portion that places planar segments (20a, 20b) of the deflector blade on opposite sides of the uncut portion in offset planes; a third grid formed of a third set of spaced-apart and parallel-extending deflector blades; and a fourth grid formed of a fourth set of spaced apart and parallel-extending deflector blades that are interleaved with and cross the third set of deflector blades at a preselected angle, adjacent ones of the interleaved deflector blades in the third and fourth sets each having opposite ends and side edges, the side edges having uncut portions that join the adjacent ones of the interleaved deflector blades along a transverse strip where the deflector blades cross and cut portions that extend from the uncut portions to the opposite ends of the deflector blades, the deflector blades in the fourth grid each having a bent portion that places planar segments of the deflector blade on opposite sides of the uncut portion in offset planes, wherein one of the ends (22, 24) in at least some of the deflector blades in the first set is uncut and is interconnected with an uncut one of the ends of the deflector blades in the third set along a reverse bend that aligns the first and second grids (16, 14) of deflector blades (18, 20) with the third and fourth grids of deflector blades, characterized in that the deflector blades of the first set are planar and the deflector blades of the third set are planar.