If we go by what the authors of the RB show, a Blacklock skillet would have an outside heat ring, be side gated, have a raised size number on top of the handle, and a raised molder's mark on the bottom at 6 o'clock. The last three characteristics are consistent with early Lodge skillets. If Blacklock had made a move to inset heat rings before it burned is uncertain. Those who are currently trying to identify Blacklock skillets and establish a timeline also cite the shape of the rib on the underside of the handle as having significance.