From the limited information provided, it sounds like you need "True-Arc" pliers. They come in two versions, Internal and External. You need "External" I think.
Internal True-Arc pliers compress the ring, like a regular pair of pliers, when squeezed.
External Tru-Arc pliers expand the ring when squeezed.
The Internal pliers are made similar to regular pliers with two crossed pieces of metal. When you squeeze the handles the jaws move closer together.
The External pliers are made with two pieces of metal that are hinged but do not cross. When you squeeze the handles the jaws move farther apart.
Hope this helps. I got mine at Radio Shack several years ago.
Clancy