Abstract: The notched base ring comprises a base ring sheet body including a top portion, a bottom portion, a first end connecting the top portion to the bottom portion, and a second end connecting the bottom portion to the top portion. The top portion includes a plurality of attachment lugs and defines a plurality of notches, each notch being at least partially defined by two lugs disposed on opposite sides of the notch, the top portion also including an angled top edge that is disposed at each of the attachment lugs, and the bottom portion includes a bottom support edge.