Kohler 2974D Mode D'emploi page 12

Install the Valve Stem Adapter (cont.)
If the mark or your finger is below the edge of the plaster
guard, perform the remaining steps:
Slide the pencil along the steps until the mark or your fingers are
even with the top edge of the plaster guard.
Note which area of the plaster guard the pencil is touching.
If the pencil is touching the step labeled "1," use the 1-3/8" (35
mm) (medium wall) valve stem adapter and the 1-3/8" (35 mm)
screw.
If the pencil is touching the step labeled "2," use the 1-7/8" (35
mm) (thick wall) valve stem adapter and the 1-3/4" (44 mm)
screw.
If the pencil is touching the step labeled "3," use the 7/8" (22
mm) (thin wall) valve stem adapter and the 3/4" (19 mm) screw.
1204801-2-A 4 Kohler Co.