The top edge of the tape has normal graduations, while the opposite edge has 1/2 scale graduations. To divide 57-5/8" in half, just read 57-5/8" from the bottom scale – it's that simple.
Each tape is housed in a durable plastic case with rubber finger grips on the top and bottom. Available in two sizes. The 16' is 11/16" wide; the 25' is 7/8" wide. Clever and useful tapes.