0.031" 1pcs,0.033" 1pcs ,0.035" 1pcs,0.037" 1pcs The accelerator pump nozzle is made of brass, which is corrosion-resistant and is processed by a high-precision CNC lathe from Japan with precise dimensions.Easy to replace, the copper gasket is durable and long-lasting. Vintage improved brass Holley acceleration pump jet Straight jets For 2300/4150/4160/4500 carburetors Includes gasket, which turns into a bowl when squeezed. Holley 121-131 121-133 121-135 121-137 Accelerator Pump Discharge Nozzle.1 order contains 4 pcs, sizes are: 0.031“ 1pcs,0.033” 1pcs ,0.035“ 1pcs,0.037” 1pcs