Hopper opening / Funnel

In the cold winter,Hot-water-bag is our indispensable important products through the winter.However, in the use prod-ure, if the water is too nasty and plugs up the blasthole, air can't discharge in time and leads to water filled out, which is not conducive to the personal safety.This design improve the blasthole of the bag into the shape which is similar to a funnel,which makes the air exhausted effectively and reduces the risk of user being scalded.It would be more convenient to use,if the bag have a handle on its top.