It is equipped with a cylindrical dedicated filling spout on the top, which can connect equipment feeding pipes or allow precise manual feeding. Feeding is concentrated with no dust, spillage or leakage for neat and efficient filling. The filling spout can be tightly bound for full sealing after filling to resist dust, moisture and material overflow. The fully closed flat bottom has no discharge outlet, delivering an intact and sturdy bag structure with stable load bearing and tidy stacking. Without weak bottom openings, it boasts strong compression and deformation resistance. Combining convenient feeding and sealed storage, it is far more practical than fully open-top bags.