It is common to see 125mm ducting used in homes for HVAC purposes, mostly with boilers. It helps to properly ventilate gases out of the home. This material is flexible and rarely kinks. It creates a tight seal with the use of clamps so that toxins are not inhaled. Flexible options are also handy in the kitchen for exhaust hoods and in utility rooms where ventilation ducting is required. Fixed compositions, those that do not move, are often made of a PVC material. This is ideal for use outdoors in garden spaces for drainage purposes under the surface of the ground.
It is best to trim the ducting after the length needed is properly measured. A sharp utility knife should be used to prevent tearing of the exterior or potential punctures. You can find 125mm ducting in flexible and fixed compositions on eBay for your home improvement needs. Replace the ducting from your clothes dryer to the outside of your home for proper ventilation.