4mm id Sinking Air Line
Purchase by the Mtr exactly how much you require…. or by larger amounts
4mm id sinking air line a great product and very nice quality too,we use this ourselves on our main ponds in the shop and find it works perfectly, so much nicer than having all the air lines floating.
Internal Diameter 4mm
External Diameter 7mm
This fits perfectly onto our 50mm round air stones