With regard to the operation of this bleed valve first I was more than skeptical. Due to the low price, I ordered it anyway times.
Lo and behold, I was disabused !!! No strenuous pumping, no leaking water !!! Simple valve on the screw cap of the waterbed screws, push air towards the valve, unscrew the valve cap on it - done !!! Result: No annoying air bubbles in the water bed.
Low-cost alternative, which I would definitely recommend !!!