A Discussion of the types of Matte Boxes for tric effects are lens shade produced by Bolex.
MatteBox MB 450W Super Wide
SmallRig Mini Matte Box Pro and Lite Released
Tilta Matte Box review - good stuff from China? - Dan McComb
Eiger Matte Box Pro Kit: VND 1-5, VND 6-9, Glow Mist, Gradient
Camera Lens Matte Box, Lightweight Matte Box, Matte Box Dslr
The SHAPE 2-Stage 4 x 4 Matte Box accepts lenses with up to a 100 mm front outside diameter. It mounts to 15 mm LWS rods and utilizes a swing-away design, which lets you perform quick lens changes without having to remove the matte box from your rods. You can adjust the height of the matte box in relation to the rods, which comes in handy when your lens center to rod center height is slightly off from the standard. Two rotating filter stages support the use of 44 filters.
Shape Matte Box 4x4
Matte box - Wikipedia
Should You Buy the Tilta Mini Matte Box? (Tiltaing TIMBT15 Review - Best Matte Box for Video?)
FOTGA S-light3 Lightweight 4×4 4×5.65 Clip-on Mini Matte Box for DSLR Mirrorless Camera – FOTGA Official WebSite
Matte Boxes and Lens Hoods can make your pictures sharper, also a look at the Alphatron Matte Box.
Why You Should Use a Matte Box On Your Next Shoot
Arri LMB-15 Matte Box