Here is the matte box that I’ve been using on my latest film projects. It is affordable, but of very good quality. Thanks to the carbon-fibre construction and aluminum frame, it is sturdy yet light. It has a 2-stage filter tray that holds 4X4 inch filters, with one of the filter trays being rotatable.
Also, the whole matte box swings away, making it easy to swap out lenses.
The box mounts onto two 15mm rail rods and has a vertical height adjustment.
Here is the full review