Abstract: A locking system which includes landing nipples connectable in a well flow conduit and a lock mandrel to which well flow control devices are connectable. The landing nipples have an unrestricted full bore flow passage with a locking groove and profiled locating recesses with one square shoulder in the flow passage. The lock mandrel may be lowered through full bore landing nipples to automatically locate in the full bore landing nipple in which the lock mandrel is to be operated to lock and expand a seal system to sealingly engage the landing nipple. The lock mandrel utilizes locking lugs engageable in the landing nipple locking grooves. The automatic locator device has locating keys with one or two square shoulders, which locate the lock mandrel in a landing nipple. After operating, the lock mandrel is releasably retained locked and sealed in the landing nipple. The lock mandrel may be operated to disengage the landing nipple and permit the seal system to retract for retrieval from the landing nipple.

Abstract: A combination step and extension ladder manufactured of composite material such as fiberglass is disclosed. The inner and outer side rails are molded fiberglass so that the fibers are angularly oriented with respect to the longitudinal axis of the respective side rail. Hinges are provided on each of the inner side rails of the ladder so that the ladder may be folded and unfolded from a step ladder configuration to a straight extension ladder configuration and vice versa. The inner side rails are telescopically mounted within channeled outer side rails so that the inner side rails can be extended to increase the height of the ladder in either configuration. The outer side rails have a foam strip molded into one side such that the ladder rungs between the outer side rails are supported by both the fiberglass and the foam strip.