Conn bore sizes, as shown on its brass instrument model designation list, are
coded as a whole number, or a number and fraction (e.g., 1 1/2). The attached chart
translates these to decimal-inch and millimeter dimensions.

	Conn rarely stamped its bore designation code on an individual instrument.
Instead, on instruments built before about 1915, a bore size mark such as
"S", "M", or "L" was often stamped below the serial number on the middle valve
cylinder.

	After about 1927, the bore size could be determined by finding the stamped
model number on a particular instrument, and referring to Conn's brass instrument
model designation chart to find the bore designation code applicable to that model.
Conn brass instrument models which had identical outward appearances were
nevertheless assigned different model designations to differentiate among their
different bore sizes (e.g., Conn 22B, 26B, and 28B trumpets).