This is for waste water use and not rainwater drainpipe use which is a different product. Solvent weld reducer designed to fit into a larger solvent weld fitting (they cannot be inserted directly into a pipe) and then accept a smaller solvent weld pipe.
eBay
1pc Air Conditioning Copper Tube Female-Male SAE Flare Thread Tube Adapter 1/4 3/8 1/2 5/8 3/4 Reducer Joint Brass Pipe fitting
Aliexpress UK
40mm Boss Adaptor Reducer Seal Ring (Grey). Colour: Grey. Appliance repairs must always be carried out by a suitably qualified engineer or technician. UNIVERSAL Washing Machine Drain Hose Long Cold Water Fill Extension Pipe 3.5 2.5.
eBay
M4 M5 M6 M8 M10 Metric Female To Male 304 Stainless Steel Reducer Bushing Pipe Fitting Connector Coupler High Pressure Gauge
Aliexpress UK
Solvent weld reducer designed to fit into a larger solvent weld fitting (they cannot be inserted directly into a pipe) and then accept a smaller solvent weld pipe. White Solvent Weld Waste Pipe Fitting.
eBay
Hose Barb 4mm 5mm 6mm 8mm 10mm 12mm 14mm 16mm Tee Type Reducing Brass Barbed Pipe Fitting Reducer Coupler Connector Adapter
Aliexpress UK
Solvent weld reducer designed to fit into a larger solvent weld fitting (they cannot be inserted directly into a pipe) and then accept a smaller solvent weld pipe. White Solvent Weld Waste Pipe Fitting.
eBay
3/8"1/2" 1/4" Elbow 90/45 Degree Angled F/F Stainless Steel SS304 Female Male Threaded Pipe Fittings Reducer Plumbing connection
Aliexpress UK
This reducer will allow you to connect 20mm (3/4") Black convoluted waste pipe to a vast range of 28mm push fit adaptors/fittings. Makes installation easier and straightforward.
eBay
6 8 10 12 13 14-50mm Hose Barb Fitting Union 304 Stainless Steel Pipe Fitting Connector Nipple Coupler Reducer Water Gas Air Oil
Aliexpress UK
These Solvent Weld fittings & pipe require solvent weld glue to seal them. Pipe Sizes Information: CHECK YOUR SIZE BEFORE YOU ORDER.
eBay
Red Car Intercooler Turbo Intake Pipe Coupler Universal Silicone Tubing Braided Hose Straight Big To Small Reducer ID 16mm-180mm
Aliexpress UK
40mm to 32mm push fit reducer. 40mm to 32mm reducer.
eBay
Universal Straight Silicone Reducer Hose Intercooler Turbo Intake Pipe Coupler Hose Red Black Blue
Aliexpress UK
McAlpine Reducer 32mm x 38mm ST28m. Easy to use.
eBay
AW® 304 Stainless Steel Reducer Bushings BSP Male To Female Pipe Fittings 1/8"1/4"3/8"1/2" 3/4"1" High Pressure 6000psi
Aliexpress UK