SWA series has 10 models that offer:the auto-cut shuts off automatically to prevent over-heat whenever its voltage drop, impeller plugged, water level under the watermark and other unusual conditions. cable base filled with EPOXY to raise humidity resistance. all O-rings made of nitrite rubber, strict adherence to CE and UL standards. three kinds of impellers, semi-open, closed, vortex are equipped for pumping various waste water treatment.