O-ring gasket set 18,64-34,52mm (12 different sizes / 180pcs) - MotoMoto
uxcell Nitrile Rubber O-Rings, 52mm OD 46mm ID 3mm Width, Metric Sealing Gasket, Pack of 10: Amazon.com: Industrial & Scientific
Amazon.com : (2 Pcs) 52-72MM Step-Up Ring Adapter, 52mm to 72mm Step Up Filter Ring, 52 mm Male 72 mm Female Stepping Up Ring for DSLR Camera Lens and ND UV CPL
Ring Size Guide and Chart | H.Samuel
Size Guide: Rings – Paul Valentine
52mm A Size Adaptor Ring | SRB-Photographic.co.uk
Size chart | ethnopur
Starlight Xpress Adaptor 52mm (mamă)
Meking Adapter Ring for DSLR Square Filter Holder 49mm 52mm 55mm 62mm 67mm 72mm 77mm 82mm for Option Compatible Cokin P Series