The opener is made of stiff plastic with a silicone insert that grips the top of a bottle or jar. You open the jaws and slide the jar lid under the opening. Squeeze the handles and twist, and the cap comes right off. You can't tell the size of the opener from the product listing , so I included a short video. There are 4 decreasing size openings to fit various bottle sizes. In the video, I use this on a pasta sauce bottle and it fits perfectly.
The set also comes with a second opener that works with soda bottles and pull-top cans. Between these two openers you should be able to open almost any bottle or jar.
Everyone in the house appreciates having this set!