Kair 100mm / 4 inch Ceiling Vent Diffuser with Retaining Rings High-quality adjustable wipe-clean plastic air vent valve with retaining ring. The discreet yet aesthetically pleasing design is suitable for flush fitting against ceilings and walls. Easy to install and durable. For permanent fixings, you can seal the joints with a method of your choice (Popular options include silicone sealant, solvent cement, tape or hose clips for flexible ducting. This dual purpose outlet / inlet can be used to supply or extract air. Ideal for use with 4 inch / 100mm in-line fans. Built to last out of high-quality white Polystyrene/Polypropylene plastic material Max / Min Temperature: +60c / -15c Suitable to use in compliance with Part F Building Regulations Genuine Kair Ventilation product. Perfectly suited for use with your Bathroom or Kitchen extractor fan, Hydroponics, or In-Line Extract Fan. This reducer can be used as a part of a long ductwork run for a variety of purposes including whole house ventilation, passive stack vent, positive input, air conditioning, HVAC, and Heat Recovery Systems. Genuine Kair Product & covered by the Kair 100% satisfaction guarantee. If you have any questions please do not hesitate to ask fellow purchasers via the Customer Questions & Answers system.