Abstract

A seal includes a first elastomeric ring and a second elastomeric ring. The first elastomeric ring has an annular cavity, and the second elastomeric ring is in the annular cavity. In another embodiment, a seal includes a first elastomeric element and a second elastomeric element. The first elastomeric element has a length extending along an axis, a first surface facing radially outward with respect to the axis, and a second surface facing radially inward with respect to the axis. The second surface defines a cavity extending along the axis. The second elastomeric element is in the cavity and has a first surface facing radially outward with respect to the axis.