Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Very effective

I bought the large size Nosovent, which I found to be very effective in increasing the air flow through both nostrils. I should mention that I did experience some minor irritation initially until the plastic material "gave-in a bit.After a few days' use the Nosovent developed a slight curvature and became more comfortable so that there is no irritation in the morning. I think it is a great product and definitely preferable to a septoplasty.