Lee Filter Foundation kit; the 100mm system. Lee Filter Holder

Description

Note: This is not the newest version of the product with the knobs. It has a brass plunger instead.
The LEE Filter holder is designed to be as flexible as possible, allowing the photographer to create a filter holder that will match his or her individual needs and style of photography.
To assemble the unit, the holder plate should be placed on a flat surface. The brass finger bolt is a plunger that pulls in and out. The filter guides can then be stacked on the unit and screwed into place. Place an equal number of guides, in the same order, on both sides, as these make up the slots into which the filters slide.
The standard guide is for 2mm filters. This takes LEE resin and mounted polyester filters. The #1 guide will take unmounted polyester filters.
There are other accessories available;  to go up to 105mm, for example.
Adorama says  " The holder attaches directly onto the lens itself and such close proximity allows the maximum possible angle of view without vignetting. The unit also has added advantage of using standard 100mm filters."
It will include the box, the bag, the holder, and the 6 elements used to customize the size, plus the assembly screws. As shown in the picture, two elements are already installed. It has never been used.