LIGHTNIN 809411 A310 3.8" Dia. Axial Flow Hi-Efficiency Impeller, 5/16" Bore. The A-310 Impeller is standard on LabMaster® mixers. These Axial Flow Hi-Efficiency Impellers have laser designed paddles that develop 50% more mixing action for high-flow, low-shear mixing. The A-310 design also provides geometric similarity for accurate scale-up to larger Lightnin mixers.