can cover / cover

Opened can may be as dangerous as a sharp blade of knife. It can cause a cut to careless children.
We are living with a potential risk of suffering a cut cause by favorite canned food, indeed.
Cover is needed to protect or store food inside an opened can in a hygienic way.

Just as a knife is maintained in a sheath, a cover made of elastic rubber material gradually goes up to wrap the opened part of an opened can according as it is opened.