Genustech GARD-NK Donut Adaptor Ring with Nuns Knickers

Where the plain donut steps down to a known ring size, the GARD-NK closes the gap on anything. A 105 mm plastic ring seats in the matte box, and an elasticated black-out fabric skirt, the part the industry has always called nuns knickers, wraps around the barrel of the lens and blocks light entirely.

That makes it the part to reach for with a zoom that changes length, or with a lens whose barrel diameter does not match any adaptor ring you own. It is the same job as the GARD, done with fabric instead of a machined lip.