BXXX is a style reference. See the Current Bracelet Designs for examples of other styles.
SNXXXXX is the serial number of a specific piece of jewelry. Not all pieces have a serial number as applying it might damage the piece.
B056 SN20013 is a very dainty bracelet made out smaller gauge wire than I typically make it out of. It has been heat hardened to hold its shape. It is a size 52 which means that it will fit a wrist that is approximately 6.5" in circumference depending on whether or not you like a cuff bracelet to be tight or loose.
If SN20013 is not your size, B056 is a Current Design and a new bracelet can be made to fit your wrist. This will require that you contact me by phone or email.