Wherever there is milkweed there will be Monarch butterflies. The monarch is widely distributed across North America, from Central America northwards to southern Canada, and from the Atlantic to the Pacific coasts.
The pitch diameter (often called the effective diameter) of a parallel thread is the diameter of the imaginary co-axial cylinder which intersects the surface of the thread in such a manner that the intercept on a generator of the cylinder, between the points where it meets the opposite flanks of a thread groove, is equal to half the nominal pitch of the thread.
For example, a number 40 chain would have a pitch of four-eighths of an inch, or 1/2, and would be of the standard dimensions in width, roller diameter, etc. The roller diameter is nearest binary fraction (32nd of an inch) to 5/8ths of the pitch; pin diameter is half of roller diameter.