Each QPL MIL-STD-1553 interface transformer has an arbitrary part number or "Military Designation Number" which identifies turns ratio and physical package.
These Military Designation Numbers and corresponding information are tabulated on pages 11, 12, and 13 of MIL-PRF-21038/27. The link is provided here so you can specify by the appropriate Designation Number.
Or, if you prefer, just fill in the questions on the inquiry form, and we'll contact you to facilitate the part specification process.