Rock-It Spherical Diameter Plug Gages

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Easy to use Spherical Plug Gages.

Gages entire bore precisely and effortlessly!

Supplied from .250” up to 22.00” diameters (or metric equivalents) in hard steel (RC-63).

The ROK-IT bore gage with its true spherical form eliminates the difficulties and limitations encountered in the use of the conventional type of “plug” or cylindrical gage which has maximum or excess frictional area contact with the work.

It will positively “accept” or “reject” down to the finest limits. It is extremely light and easy to handle. 4” diameter double ended gage weighs 1 lb. A blind operator can inspect bores with ROK-IT. It is not possible for the gage to seize or jam in the work. Gages can enter bore at angles as in the case of a component in a machine where quill is in the way. It reveals back taper in blind bores. ROK-IT gages work without having to line up gage perpendicular to bore. Hence it is self centering. ROK-IT gages are easily and quickly inspected with “Supermike” or any comparator (use flat anvil only).

Significant Advantages:

Gages to finer limits: 30 to 50 X greater life: Gages entire bore surface (line contact instead of point contact) :Gage cannot jam in bore: Can be used as an approach gage: Can check recesses: Enters bore from any angle: Gage in 1/5th the time: Checks shallow counterbores and blind holes: Little or no skill required. Checks entire geometry:—BELLMOUTH—HOURGLASS BARREL SHAPE—TAPER and BACK TAPER and OVALITY.


Ordering Information

When ordering, please provide:

  • Tolerances, e.g. GO—3.500”/NO GO 3.501”.
  • Class required: e.g. XX, X, Y, Z.
  • Gage design: e.g. Whether single ended or double ended; For deep bore model specify length of parallel rods (allow approx. 3” for handling).
  • Special marking required on gage, e.g. any code which you may wish to imprint, space permitting.
  • Single ended gages—Do you want “GO” or “NO GO”.

At no extra charge:

  • All metric sizes
  • Handles etched with size only
  • Extra charge for additional etchings
  • Gage handles


Please specify your Rok-It gaging requirements per the following and we will promptly supply pricing and delivery.


FOR GAGES from 12” to 22” diameters—ask for SPECIAL QUOTATION. Class XXX on quotation. Single-ended gages are recommended over 6” diameter, although double-ended gages will be supplied if specified. Standard handles supplied are 4” long. Handles required over this length are supplied at an additional charge per inch over standard. The above prices apply to both standard and non-standard gage sizes.


NOTE: RAPID DELIVERY ON ALL METRIC SIZES—at same price as above. CERTIFICATION: at an additional charge per net per member.

Shallow Counterbores


(A) Center line of sphere on gage is ground forward to a position close to the front face of gage members.
(B) You can see and feel gage bottoming in the shallow counterbore. Nominal extra price add on for this feature.


When Ordering: Please Specify “Depth of Counterbore”.
For COUNTERBORE APPLICATION add additional charge net per double ended gage for moving center-line forward (price applies to all diameters). Bores deeper than .3125” do not need special application.

Deep Bore Gages

On articulated handles - supplied from 1” dia. And larger.

  • Ideal for checking extra long bores
  • Gaging a recess or chamber within a bore
  • Enter bores where entrance bore is smaller than bore being checked
  • Handle lengths up to 48 inches


Flexbar Rok-It Deep Bore Gages on articulated rods (parallel rods)

OVERALL LENGTHS: Up to 12”, 12” - 24”, 24” - 36”, 36” - 48”.
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