The Engel Rechargeable Air Pump Gen 4 is the latest generation lithium-ion rechargeable aerator for live bait coolers. USB-C rechargeable with extended battery life to keep your bait alive all day. Quiet operation won't spook fish in kayaks or small boats. Multiple speed settings let you match the aeration to your bait load. Compatible with all Engel live bait coolers. A major upgrade over D-cell battery pumps no more buying batteries.