Potty Seat comes with partial assembled condition. Needs to fit the potty handle only. Potty handle comes with fitting nut which needs to fix in body hole presents at front side. While fitting the handle do not tighten the nut over as it will slip. Just tighten the nut till its tight enough for the handle to not move. If over tighten it will slip and cause the handle to move or comes off. While tightening the nut make sure the handle is properly inserted in the hole of the body and is full fit inside the groove area. Potty Size: If baby health is slimmer then can be used up to 2.5-3 years. If someone baby having healthy body (BMI) then can be used up to 2 years old baby. Ideally this is perfect size for 5 - 24 months old baby.