Bally/Williams A22-550 Coil (550 winds of 22AWG enamelled copper wire).
This is a general-purpose Bally/Williams coil used in a range of early EM machines. Probably the most common type of coil for step-up score drums.
It is comprised of 550 winds of 22AWG enamelled copper wire on an A-series coil bobbin with solder lugs. As it is generally used in EM machines, it does not include a flyback diode. If you are planning on using this in a more modern machine, add a pack of ten 1N4004 diodes to your order.