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How do I measure different types of shells?
Last Updated: 09/13/2009
The photo below demonstrates how we measure each style of shell.
  • Round Shaped Opening Shells are measured inside left edge to inside right edge.
  • Elliptical Opening Shells are measured from just inside the left lip to the inside right edge.
  • Oval Opening Shells and D-Shaped Opening Shells are measured more for the "wearable" space, excluding the extreme left end or right end.

The image below shows how to hold the caliper. The measurement is read below the zero on the sliding piece. The shells depicted would all be wearable by the same size crab.

Notice that the D-Shaped and Oval opening shells are about 1/4" larger than the equivalent Round opening shell. The Elliptical opening shell is in between. You will want to take this into consideration when you are purchasing shells for your crab.

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