I purchased the app thinking it would be great to use during my day when I find myself with a few free minutes. The application itself is a simple design and works fine. Unfortunately, some of the content is incorrect. I found enough errors after just a few hours of use to cause me to not trust the remainder of the content. So due to this loss in credibility, the app is useless to me. One of the most glaring encountered was that the card for dollar duration incorrectly gives the formula for duration. If they get something this simple wrong, it is clear that the person creating these cards does not hold the CFA designation and does not understand the content of the cards. I emailed the company regarding two of the errors I found and asked for a refund. They never responded to my email.