4mm Check (non return) Valve – x2

This 4mm Check (non return) Valve set is perfect for protecting your aquarium or pond air system from backflow.

• Each 4mm Check (non return) Valve fits standard 4mm internal and 6mm external silicone or PVC air tubing.
• Made from high-grade plastic, they are strong, durable, and built for long-term use.
• Ideal for sponge filters, breeder boxes, air stones, and DIY CO2 systems in freshwater or marine aquariums.
• Check valves prevent water from flowing backward into air pumps, protecting your equipment from damage.
• Essential for all air systems in aquariums, ponds, or professional fish room setups.

Designed for use with bio-filters, CO2 cylinders, or custom air distribution networks.
Suitable for both home aquariums and larger commercial aquatic systems.
Easy to install and compatible with all standard air pumps and tubing sizes.
Helps maintain consistent airflow and pressure across all connected equipment.
Works well with marine, tropical, cold water, and planted aquarium setups.
Affordable, reliable, and easy to maintain for peace of mind.
Supports safe and stable operation of air-driven aquarium devices.
Use one valve per airline to prevent water from reaching your pump.
Great for hobbyists, breeders, and aquatic system builders.
A must-have component for any air or CO2 aquarium system.