• Range: 5/16" - 6" (8mm to 150mm), 6 pc set includes:

• 1 gage: 5/16 - 1/2" range x 4.20" overall

• 1 gage: 1/2 - 3/4" range x 4.40" overall

• 1 gage: 3/4 - 1-1/4" range x 4.40" overall

• 1 gage: 1-1/4 - 2-1/8" range x 5.85" overall

• 1 gage: 2-1/8 - 3-1/2" range x 5.85" overall

• 1 gage: 3-1/2 - 6" range x 5.85" overall

• Spring loaded with locking knurled knob

• Stainless Steel Construction

• Gage expands in a hole to be measured (locks in place and then removed to determine final hole size using a micrometer or calipers).

• Get exact sizes of holes, slots, bores, or recesses

• Rigid handle and double action design (self-centering) for quick checking of inside measurements

• Constant spring tension for uniform feel

• Contact points are hardened tool steel and precision ground in the end measuring radius

    Steps       

• Collapse the telescoping gage.

• Secure the telescoped gage by turning the knurled ring, lightly tightening  it.

• Insert the gage into the bore to be measured.

• Roughly align the handle parallel to the axis of the bore, and release the  knurled ring. A little practice - before measuring - locking and unlocking the  ring will give the user a knack for gradually extending the gages tubes against  the bore without having them slap vigorously against the bores surfaces.

• Lock the knurled ring very lightly, then rocks the gages handle about the  bores axis. Properly accomplished, the user will discern a light "drag" on the  gage as the lightly-rounded gage ends engage the bores surface at its largest  diameter. If no drag is felt, the gage tubes are NOT ninety-degrees to the bores  axis and aligned at its largest diameter. The user MUST wiggle the gage handle  until this is accomplished.

• Tighten the knurled ring a bit more to ensure that the gage ends are held in  position for measuring.

• Using an outside micrometer or a vernier caliper, rock the telescoping gage  until a drag similar to that felt in the bore is felt against the faces of the  measuring device