The UMB-1 Universal Matte Box (Clamp On) is the rod-free configuration in Wooden Camera's UMB-1 system, clamping directly onto the lens barrel rather than mounting to support rods. It has the same 143mm diameter opening as the rest of the range, fitting lenses up to 143mm O.D., and carries two rotating 4 x 5.65" filter stages as standard, with an optional third stage available as an add-on. A set of clamp-on adapter reduction rings is included, in nine sizes — 80, 87, 95, 104, 110, 114, 125, 134 and 136mm — so the box seats directly on the lens without a rod-mounted bracket. NATO accessory rails run along the left, right and top of the housing for mounting further accessories, and a folding top flag is included, blocking stray light from above the lens and folding flat for storage. It shares its opening, filter-stage and rail layout with the Base, Swing Away and Pro configurations, differing in its clamp-on mount and included accessories.