Why is Amazon reporting 999 or N/A for stock quantity on some ASIN's?
The reason AZInsight only shows 999 is because Amazon does not want a buyer to see the total true quantity a seller has available for sale when its over 1000 units.
The reason AZInsight shows N/A is because Amazon does NOT allow you see the total quantity a seller has unless you sign in and add your zip code or complete the checkout process.
See examples below: