this section is mainly focus on the develpoment of bb movement from the 30's. there are 3 series of movement being 1)8 3/4 with watchmaker intruction 2) autor rotor 3) perpetual.
examples in the picture is a full watchmarker instruction 8 3/4" prototype movement
50's large bb with explorer dial
this is a very pretty all original larger bb with 35mm diameter without counting the crown, the dial is a sunken type, very clean and all original bb, runs well and keeping good time, come with an original rivited band.