The Stabila 37540 Type 196 Jamber Set 78 in. Level Plus Type 80 T Extendable Level (24 - 40 in.) has a heavy duty profile designed to fit in a standard 80 in. door opening. This allows a contractor to plumb down the jamb legs and eliminate bows in the door frame. The 80 T fits most door openings found in residential construction. Achieve a perfect fit for headers by simply locking the 80 T to the exact door sizer using the measuring scale on the level.