Grade 510, 23 diamond, ruby and sapphire jewels adjusted to 5/6 positions, manufactured from 1911 to 1918 a total of 483 movements in 13 runs make up this grade. Model 4 size 12/14 open faced; bridge movements of the highest quality, with double roller and patent micrometric regulator.
Observations, The majority of movements have broad striped pattern demaskeening named Hallmark and Ariston. The remainder are crosshatch pattern and named Illinois and Illinois Watch Co. The size 12/14 movements have a size 12 bridges and size 14 pillar plate and have a stretched enamel dials that are not recessed into the pillar plate, they require special cases. Hallmark models adjusted 6 positions marked on the pillar plate, with burnished set jewels, found with Hallmark double sunk metal dials and have The Hallmark Watch on the case cuvette; Ariston USA and Ariston Rated models adjusted 5 & 6 positions marked on the center bridge with screwed set jewels, Ariston double sunk enamel dials and Ariston marked cases with M F & Co: Illinois models adjusted 6 positions marked on the barrel bridge, with jewelled barrel marked on the pillar plate with screwed set jewels, the cases are marked The Springfield Watch on the cuvette.
Variants, Two types of escapement bridges can be found, most of the movements have a two fingered bridge except the Ariston models that have a full plate escapement.
Description, 23 extra quality diamond, ruby and sapphire jewels; gold settings; accurately adjusted to temperature, five or six positions and isochronism; very carefully timed; compensating balance having gold screws; steel escape wheel; double roller escapement; red ruby roller and pallet jewels; jeweled barrel; best quality Breguet hairspring; Phillipe coil; patent micrometric screw regulator and first quality mainspring; unusually large dial is a special feature of the watch all were factory cased.