A cap for selective attachment with a threaded opening includes an outer cover and an inner portion, the inner portion lying at least partially within the outer cover and having threads engageable with the threaded opening and a set of circumferentially-spaced teeth arranged to selectively receive torque from manual rotation of the outer cover. A slider in constant driving engagement with the outer cover is selectively engageable with the teeth of the inner portion to transmit torque from the outer cover to the inner portion. An actuator is provided to actuate the slider into and out of engagement with the teeth of the inner portion. A lock is provided accessible from outside the outer cover and being coupled to the actuator. A locked state of the cap is one in which the slider is removed from engagement with the teeth of the inner portion by the lock and actuator and an unlocked state of the cap is one in which the slider is engaged with the teeth of the inner portion.