The ACE Turbo-trim wheel trim rings are "sister" parts to the ACE Mercury Wheel Discs. These parts are similar in construction, made of bright anodized aluminum and containing similar functional right and left handed louver type air scoops. The trim rings cover only the outer perimeter of the wheel so forced air flow would be limited to slots in the wheel between the rim and the center disc. There would be multiple part numbers for wheels of different diameter and with various wheel width and offset, depending on how much of the wheel rim would protrude outboard of the center disc.

This was not a factory option for the MGA, but it could have been a local dealer offer or open market aftermarket part. It is therefore a period accessory part for the MGA.