| 摘要 |
A level including an elongate hollow frame with two sidewalls and a topwall extending therebetween. A central vial is within a topnotch formed by removal of a topwall section and adjacent sections of sidewalls including notch-defining bottom and side edges. An integral inner vertical wall extends between the top and bottom walls thereby reinforcing the frame along the frame length. The inventive level further preferably includes an external brace reinforcing a central frame portion weakened by forming the topnotch. The external brace includes first and second plate members each against one of the sidewalls about the notch-defining bottom and side edges and each substantially spanning a respective one of the sidewalls. A fastening member extending through the sidewalls and pulling the plate members toward each other to sandwich the sidewalls therebetween, thereby reinforcing a central frame portion weakened by forming the topnotch.
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