Round ducting adaptor to convert between 125 mm and 100mm ducting. Perfect for connecting round pipes, flexible hoses, ventilation slots and fan plugs and for applications where space is restricted. Larger end of the reducer is female. Small end of the reducer is male. Smooth internal bore for reduced airflow resistance. Manufactured from UV protected white PVC plastic. 125mm / 5 inch Side: 125mm female spigot will fill fit over male fittings (Such as bends, connectors, etc). Round 125mm ducting pipe requires a male connector/coupling.127mm Flexible ducting will fit over and require tape or metal hose clips to attach. 100mm / 4 inch Side: 100mm Male Spigot will fit into 100mm straight ducting.Can be used with rigid plastic ducting systems. Can be used with flexible ducting systems with use of metal hose clips. Max / Min Temperature: +60c / -15c.