The Foundation Kit is fundamental to the LEE Filters system. It takes standard 100mm filters, and can be constructed to take up to three filters at any one time (remember though, the more filter guides added the higher the likelihood of vignetting with wide angle lenses). The Foundation Kit, like all others, clips onto the Adaptor Ring, which in turn, screws onto your camera's lens.
The Foundation Kit comes assembled ready to go with 2 sets of 2mm Guides and is packaged in a pouch and comes with a screwdriver and instructions for altering the assembly if required.