Terminology, reference 4 = (4 x 1/8 = 1/2") B = British Standard,
-1 = Simplex (one row of teeth)
Last 2 numbers denote number of teeth
e.g. 41.38 = 1/2" pitch, Simplex, 38 Tooth Sprocket
To suit British Standard Roller chain :-
08B-1 (B.S. Reference), 110046 (Renold), 4SR (Morse)
