A coupling device is provided including a first coupling member or portion and second coupling member or portion where the second coupling member is configured to releasably engage the first coupling member. The second coupling member includes a locking sleeve or locking sleeve assembly slideably mounted on a cup body with the sleeve capable of being shifted toward an opening of the cup body to an unlocked position that permits insertion of the first coupling member into the second coupling member. The sleeve has an inner surface that covers and protects a fastening element positioned within bores of the cup body in both the locked and unlocked positions thereof. In one form, the locking sleeve assembly includes a locking device which restricts the sleeve from inadvertently shifting toward the unlocked position.