Although the building slip is not a required accessory, it makes the ship building process much easier and is recommended, especially if you plan on building several models. This building slip is for models up to 35.43" with the appropriate hull shape such as the Norske Løve. It is not necessary for the Viking ship models because the hull does not match building slip template. The notched keel is screwed into the base plate. Two guide blocks, one permanent and one adjustable to match all sizes, secure the positioning of the keel. A wooden rod ensures the foundation is stable. The square middle piece slides back and forth and is useful in positioning the frames at right angles.