2 inch or 3 inch fill water hole,Big flush volume(can more than 2.1L/S),the flush effect is better 1.2 inch or 3 inch fill water hole.2.High seal water performance,no leak.3.Big flush volume(can more than 2.1L/S),the flush effect is better.4.Adopt dual flush design,the flush water volume of big flush and small flush can be adjusted optionally,can save water source. dual flush valve 298B