CD Stromberg O-Ring for Jet Adjusting Screw 150CD 175CD types    P/N 016268

0.315” I.D. [8mm]
0.44” O.D [11.2mm]
0.07” thick [1.8mm]

this is a round section O-Ring

This O-ring [11.2mm O.D.] is the small diameter one used to seal the Orifice Adjusting Screw located at the base of the float bowl on 125CD 150CDS and 175CD-2S
Number 27 in illustration below

The larger O-ring, number 28 in illustration below is 019658, [20.6mm O.D.] located on the Bushing Retaining Screw

O-ring number 60 in illustration below is P/N 019657 located under Jet orifice bushing