De or het gummiring?

The correct Dutch article is:

de gummiring

Rule Words ending in -ing: almost always de. See the rule

How to use gummiring

the gummiringde gummiring
this gummiringdeze gummiring
that gummiringdie gummiring
our gummiringonze gummiring
your gummiringjouw gummiring
every gummiringelke gummiring
which gummiring?welke gummiring?
a big gummiring / the big gummiringeen grote gummiring, de grote gummiring