At first it looks like a rubber band. And for the most part, it's just a sturdy/durable rubber band. I had a hard time putting this on a Sony 18-250 lens because there was little stretch. This package didn't have many instructions. During installation I could not focus the lens at all. But after some trial and error I moved the bar to a few specific positions and it works great. My lens feels like a brand new lens with a large lens shift, so I can adjust the focus at will. You can also set it so that the lens doesn't roll at all. If you have trouble with lens creep, it's worth a try.
Canon EF 50mm f/1.8 II Fixed Lens - Discontinued by Manufacturer
93 Review
Canon EF 40mm f/2.8 STM Lens - Fixed Black (6310B002) for US Cameras
76 Review
📷 Nikon AF-S NIKKOR 50mm f/1.4G Lens with Auto Focus: Perfect for Nikon DSLR Cameras
76 Review
Nikon 50mm f/1.8D Lens: Perfect for Nikon DSLR Cameras!
97 Review