Solid Signal SKY32816 Non-penetrating Roof Mount Base (SKY32816) Ideal for flat-roof mounting a TV Antenna or Dish Safe & secure installation on flat roof surfaces Heavy-duty steel construction | Base consists of (6) lengths which can be assembled from 35.5" x 35.5" up to 36" x 36" square | Works with standard grade 2 bolts Requires concrete block ballast for installation (not included) Requires mast for installation (not included); see our selection of masts: SKY32817A, -B, -C1 or -D