John Blue O-Ring for DP-392.1 Diaphragm Pump | 3.53 X 190.10 Diameter
This item is highlighted as # 31 on the product illustration at the top right.
This o-ring is part # DP80329500, measures 3.53 x 190.10 in diameter, and goes with John Blue's DP-392.1 diaphragm pump.