WElinks Red Retro Bar Mount Metal Bicycle Bell, Ultra-Loud Air Horn Pump Alarm, 25mm

Had to use some additional brackets, that I had, but works well if the pump is pre-pressurised by pumping before sounding the horn.As stated by others the hose is smelly but no problem.

mine came broken sadly but it was very loud great for upsetting the neighbours if they do nights

Brilliantly loud horn, with a really smooth Big Red Button to set it off. Rather a strong petrol smell from the plastic for a good while after delivery - a good thing I wasn't spring this near the house!