They can be used for flue gas, ventilation ducts, etc. Designed to protect pipes from precipitation, as well as to increase traction.
eBay
Real Outdoor Cover for Garden Furniture, Patio Garden Furniture, Rain and Snow Chair Cover, Sofa Table and Chair Dust Cover
Aliexpress UK
Chimney Pipe Cowl. Stainless Steel for Good Weather Resistance. Wall Thickness - 0.5mm. Ø 180 mm / 7.09". Ø 160 mm / 6.30". Ø 150 mm / 5.91". Ø 140 mm / 5.51". Ø 125 mm / 4.92".
eBay
1pc, Sunshade Umbrella Cover, 210D Oxford Fabric Cantilever Parasol Cover Waterproof/Windproof/Anti-UV, Garden Umbrella Cover
Aliexpress UK
This can vary due to your boiler but for most purposes 75mm above the boiler flue. Protects your boiler from damaging rain ingress in heavy rain and wind. It was also protect your boiler in the event of guttering failure.
eBay
Shower Drain Cover Tray Waste Trap Plug Hole Cover Replacement Chromate Treatment Fast Shower Trap Cover Replacement
Aliexpress UK
Stainless Steel Pipe Rosette with Clip. Protects opening around the chimney liner and roof from rain.
eBay
Replacement of Shower Drain Cover, Chrome Plated Shower Trap Cover, Shower Drain Cover, 90mm/115mm, Detachable
Aliexpress UK
LENGTH OF ELBOW approx - 30 CM. LENGTH OF PIPE - 100 CM. MATERIAL - STEEL.
eBay
Hanging Basket Cushion Seat Cover Swing Cushion Cover Hanging Chair Cradle Waterproof Chair Cushion Cover
Aliexpress UK
LENGTH OF ELBOW approx - 30 CM. LENGTH OF PIPE - 100 CM. MATERIAL - STEEL.
eBay
1PCS Air-conditioning Protection Pipe Cover Split & Central A/C Decorative PVC Hose Cover Air-conditioning Decorative Pipe Cover
Aliexpress UK
This Boiler Flue Rain Snow Cover is designed to protect your boiler flue from rain and snow, ensuring that your heating system continues to function efficiently. Made from durable black plastic, this flue cover is suitable for various boiler brands such as Vaillant, Baxi, Ideal, Glowworm, and Worcester. The cowl design helps to prevent rainwater from entering the flue, while the vent cover ensures that the vent is not blocked. Easy to install, this accessory from the United Kingdom is a practical addition to your home plumbing system.
eBay
1PCS Air-conditioning Protection Pipe Cover Split & Central A/C Decorative PVC Hose Cover Air-conditioning Decorative Pipe Cover
Aliexpress UK
Cap in a box is a chimney cap of full value that fits in. a pizza box. - protects the chimney duct from rain or snow. Material: stainless steel.
eBay
Round Patio Furniture Covers,210D Heavy Duty Outdoor Furniture Covers Table Cover of Windproof, Waterproof, Anti-UV for Garden
Aliexpress UK