B
Balance wheel - The balance spring oscillation system is called 'the balance' for short, and provides the basis for time. The balance ensures the movement of the hands and whole accuracy of a wristwatch.
Bezel - The bezel is a component of the watch case. Previously it was the ring that fixed the protective crystal 'glass' of a watch and screwed it down tightly to the case. Today the bezel is often rotatable and equipped with a tachymeter or indices (indicators).
Bracelet -This is the strap that attaches the watch to your wrist. Bracelets are available in leather, stainless steel, but materials such as nylon and rubber are also used.
Batgirl - This is the nickname for the Rolex GMT-Master II Ref. 126710BLNR with a blue and black bezel.
Batman - This is the nickname for the Rolex GMT-Master II Ref. 116710BLNR with a blue and black bezel.

Breitling -Breitling are a Swiss luxury watchmaker founded in 1884 by Léon Breitling. The company is known for its fabulous precision-made chronometers originally designed for aviators.
Bremont - A luxury aviation-themed British watchmaker based in England. With all the watches designed, manufactured, and assembled in England, Bremont Watches is proudly flying the flag for British watchmaking.
Breguet is one of the oldest surviving luxury watch, clock and jewelry manufacturers, founded in Paris in 1775. Abraham Breguet also invented the world's first self-winding watch in 1780, as well as the world's first wristwatch in 1810.
Black Bay - An incredibly popular model of Tudor watch Originally created for Divers. The Black Bay has all the characteristic features from past models in the brand’s history. Like its domed dial inspired by the first Tudor diving watches. You can find this version here at Watch Buyers -

Watch out for letter C coming next!