Sometimes known as a 'Boston Valve' this two-way inflation Screw Valve is mainly used with Dingys and air mattresses but is also used on some inflatable Pools. It screws in to fit a 2cm diameter hole.Please Note: We reccommend you measure the hole prior to ordering to make sure it is the correct size and part.Safety Information:Warning. Not suitable for Children under 3 years.Warning. Only for domesic use.