Where I live the humidity is very high, around 70/80% average.
I bought this product to protect my guitar, a fine one, together with a hygrometer.
Perhaps due to the excessive humidity already present in the guitar case, this product did not last long, a way less than the declared "two months". With three pouches, It was barely able to keep the humidity under 60%.
However, I cannot blame this product.
I just think that it was not very suitable in my case.
I solved my issue by using 250g silica gel packets.