Amazon.com : Kiwifotos 58mm-52mm Step-Down Adapter Ring for Lenses (58mm Lens to 52mm Filter, Hood, Lens Converter and Other Accessories) : Electronics
SRB 49-37mm Step-down Ring | SRB-Photographic.co.uk
The Wisdom of Step-Up and Step-Down Rings | B&H eXplora
What are step up and step down rings? | Discover Digital Photography
Rise(uk) 37mm-28mm 37-28 Mm 37 To 28 Step Down Filter Ring Adapter - Lens Adapter - AliExpress
55mm-49mm 55-49 mm 55 to 49 Step down Filter Ring Adapter - AliExpress