Amazon.com : (2 Pcs) 52-55MM Step-Up Ring Adapter, 52mm to 55mm Step Up Filter Ring, 52mm Male 55mm Female Stepping Up Ring for DSLR Camera Lens and ND UV CPL Infrared Filters :
Metal Filter Ring and Retainer 55mm
SKF 6211NR Open Ball Bearing With Snap Ring 55mm x 100mm x 21mm - Ashley Power Ltd