Keep your SW40 Airmax Shallow Water Series^™ Aeration System running at its best with LR50 Maintenance Kit. Over time, seals and moving parts wear and breakdown causing decreased system performance. Airmax Aeration Maintenance Kits contain the parts you need to restore your system to it's maximum potential. Kits should be installed every 6-12 months or if you experience a reduction or loss of bubbles at any of the diffusers to ensure optimum performance.