Abstract: A downhole oilwell toolstring having an adapter having a male threaded portion, a longitudinally extending tubular female housing having a female threaded portion on an inner surface of the housing, a first end located proximate to the female threaded portion, a second end located distal to the female threaded portion, and a recessed groove extending around the circumference of the interior surface of the female housing at a location between the first end the female threaded portion. The adapter has a first end that is distal from the threaded portion and a second end that is proximate to the threaded portion, and a recessed groove extending around the outer circumference of the adapter at a location between the threaded portion and the first end of the adapter. The female housing is connected with the male adapter by way of the female threaded portion and the male threaded portion engaging one another. A ring is located in the recessed groove in the adapter and the recessed groove in the female housing.