The adapter screws onto the valve and then you attach a pump / airhose to the other end, The 90 degree bend allows for much easier access between spokes etc.
eBay
BUCKLOS Tubeless Valve MTB Bike Presta Valve CNC Aluminum Alloy Road Gravel Tubeless Tire Nipples Removable Core Bike Tire Parts
Aliexpress UK
For Car And Various Truck Tires, Used For Air Inflation, For Use With Most Dual Wheels With Lug Nut Hex Of 1 1/16 In. Heavy-duty brackets mount under the lug to provide stability for the stem extender.
eBay
Bicycle Valve Cap Universal Tyre Rim Stem Covers Nozzles Light Luminous Tire Valve Cap for Motorcycle Bike Accessories
Aliexpress UK
Size: 210mm (8"). 4x Flexible Tyre Valve Extensions. High Quality Flexible Tyre Valve Extensions (8"). Professional Use Tyre Valve Extensions.
eBay
Bicycle Brass Valve Converter Presta to Schrader Valve Adapter Cap for Bike Tire Dust Cover Pump Connector Tire Tube Air Nozzle
Aliexpress UK
The adaptor screws onto tyre valve and the right angle bend allows easy access. This design allows you to use your foot pump to check the tyre pressure or pump up tires. Just remove valve dust cap and screw the 45-degree valve on then strain the valve stem.
eBay
2/4/Pcs Bicycle Tire Valve Cap Aluminum Alloy MTB Road Bike Tube Tyre Gas Nozzle Cover For Fv Presta Valve Dustproof Protector
Aliexpress UK
OVERALL LENGTH 150mm. PLASTIC VALVE EXTENSIONS. FOR TWIN WHEEL TRUCKS.
eBay
2PCS Bicycle Bike LED Lights Tire Valve Cap Flashlight Auto Car Motorcycle Tire Air Valve Wheel Spokes Light Bike Accessories
Aliexpress UK
Tyre Valve Extension Plastic 150mm Qty 10. Black extension with red cap.
eBay
5-50PCS Bike Valve Converter Presta To Schrader Adaptors Bicycle Pump Tire Adapter Aluminum Tire Valve Connectors Bicycle Part
Aliexpress UK
3Pcs Tyre Valve Adaptor. Light, easy to install.
eBay
2Pcs Aluminum Bicycle Tire Valve Cap for MTB Road Bike Tube Tyre Gas Nozzle Cover Dustproof for Schrader Presta Valve
Aliexpress UK
Size: 210mm (8"). High Quality Flexible Tyre Valve Extensions (8"). 4x Flexible Tyre Valve Extensions. Professional Use Tyre Valve Extensions. Suitable for: Cars, Motorbikes, Quads, Bikes, ATV's, Light Trucks, Trailers etc.
eBay
10pcs Aluminum Bike Tire Valve Caps Schrader/Presta Covers with Valve Stem Nuts Cycling Inner Tube Accessories for Vacuum Tires
Aliexpress UK